feat(workspace): enable and enforce unreachable_pub lint

[martintmk]

What

Enables and enforces the unreachable_pub rustc lint across the workspace, then fixes every offender.

• Adds unreachable_pub = "warn" to [workspace.lints.rust] in the root Cargo.toml (alphabetically placed between trivial_numeric_casts and unsafe_op_in_unsafe_fn). Member crates already inherit workspace lints via [lints] workspace = true.
• Resolves all offenders surfaced by cargo clippy --workspace --all-targets --all-features --locked -- -D warnings (the way CI runs clippy).

How offenders were resolved (least-privilege)

• Hand-written items (fns, methods, structs, enums, traits, type aliases, pub use re-exports) across ~20 crates: pub -> pub(crate). Applied mechanically with cargo clippy --fix; the few cases clippy emitted as pub(super) were normalized to pub(crate) for uniformity.
• cachet_tier::CacheTier: the trait is genuinely public (re-exported at the crate root via pub use tier::CacheTier), but the #[dynosaur::dynosaur] attribute macro makes unreachable_pub misfire on the generated definition. Kept pub and suppressed with an item-scoped #[allow(clippy::allow_attributes, unreachable_pub, ...)] on the trait (an item-level #[expect] is reported unfulfilled across the macro expansion, and the clippy::allow_attributes self-allow matches the existing pattern in thread_aware/src/registry.rs).
• fundle bundle test component structs (Instance / Device / Vulkan): must stay pub because #[fundle::bundle] generates a public interface over them (downgrading to pub(crate) yields E0446). Suppressed with a single module-level #![expect(unreachable_pub, ...)] per test file.

No pub struct fields were touched (unreachable_pub does not flag fields). There are no include!-generated sources or cfg-gated platform-placeholder modules among the offenders, so those suppression categories did not apply. All changes are visibility-only with no behavioral changes.

Verification

• cargo clippy --workspace --all-targets --all-features --locked -- -D warnings -- clean (exit 0).
• cargo build --workspace --all-features --all-targets --locked -- clean.
• cargo test --workspace --all-features --locked -- all pass, 0 failures.
• cargo doc --no-deps --workspace --all-features with RUSTDOCFLAGS="-D warnings" -- clean.
• rustfmt --check (stable, max_width=140) on all changed files -- clean.

Note: just format-check and the --cfg docsrs docs build use the pinned nightly toolchain (nightly-2026-05-30), which is validated in CI. The changes are import-free and do not touch doc code blocks, so the stable rustfmt check is a faithful proxy for the formatting gate.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.9%. Comparing base (963e015) to head (90aec20).

Additional details and impacted files

@@          Coverage Diff          @@
##            main    #493   +/-   ##
=====================================
  Coverage   99.9%   99.9%           
=====================================
  Files        336     336           
  Lines      24829   24829           
=====================================
  Hits       24818   24818           
  Misses        11      11           

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[Copilot]

Pull request overview

This PR enables the unreachable_pub rustc lint across the workspace (configured as warn, and therefore enforced under CI’s -D warnings) and then resolves all offenders by tightening visibility (primarily pub → pub(crate)) or adding narrowly-scoped #[expect(unreachable_pub, reason = ...)] suppressions where macro-generated public APIs require it.

Changes:

• Add unreachable_pub = "warn" to the root workspace Rust lints.
• Reduce visibility of internal-only items across many crates to pub(crate) to satisfy unreachable_pub.
• Add targeted #[expect(unreachable_pub, reason = ...)] suppressions for macro-generated public interfaces (e.g., dynosaur, #[fundle::bundle]).

Reviewed changes

Copilot reviewed 83 out of 83 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
Cargo.toml	Enables unreachable_pub at the workspace lint level.
crates/tick/src/timers.rs	Tightens visibility of internal timer APIs to pub(crate).
crates/tick/src/state.rs	Tightens visibility of internal clock/timer state constructors/helpers.
crates/tick/examples/clock.rs	Makes example-only API crate-private.
crates/thread_aware/src/closure/erased.rs	Makes erased-closure helper crate-private.
crates/thread_aware/src/cell/mod.rs	Removes unreachable public re-export by making it crate-private.
crates/thread_aware/src/cell/factory.rs	Makes internal factory type alias crate-private.
crates/thread_aware_macros_impl/src/struct_gen.rs	Makes proc-macro helper function crate-private.
crates/thread_aware_macros_impl/src/enum_gen.rs	Makes proc-macro helper function crate-private.
crates/templated_uri_macros_impl/src/template_parser.rs	Makes parser internals crate-private.
crates/templated_uri_macros_impl/src/struct_template.rs	Makes derive/template internals crate-private.
crates/templated_uri_macros_impl/src/error.rs	Makes macro parse error type crate-private.
crates/templated_uri_macros_impl/src/enum_template.rs	Makes enum-template generator crate-private.
crates/seatbelt/src/utils/telemetry_helper.rs	Tightens helper visibility to crate-private.
crates/seatbelt/src/utils/mod.rs	Tightens EnableIf constructors/call to crate-private.
crates/seatbelt/src/testing.rs	Tightens test-support helpers to crate-private.
crates/seatbelt/src/rnd.rs	Tightens test-only RNG constructors and RNG method visibility.
crates/seatbelt/src/retry/backoff.rs	Tightens internal delay iterator accessor visibility.
crates/seatbelt/src/breaker/layer.rs	Makes a test function crate-private to avoid unreachable public test items.
crates/seatbelt/src/breaker/health.rs	Tightens health/metrics internals to crate-private.
crates/seatbelt/src/breaker/execution_result.rs	Tightens helper methods to crate-private under cfg-gated telemetry.
crates/seatbelt/src/breaker/engine/probing/single_probe.rs	Tightens probing helpers to crate-private.
crates/seatbelt/src/breaker/engine/probing/probes.rs	Tightens probing state methods to crate-private.
crates/seatbelt/src/breaker/engine/probing/options.rs	Tightens probing option constructors/accessors to crate-private.
crates/seatbelt/src/breaker/engine/probing/mod.rs	Tightens probe constructor visibility.
crates/seatbelt/src/breaker/engine/probing/health_probe.rs	Tightens health probe constructor visibility.
crates/seatbelt/src/breaker/engine/mod.rs	Makes internal engine alias and helper method crate-private.
crates/seatbelt/src/breaker/engine/engines.rs	Tightens engine factory/getter visibility.
crates/seatbelt/src/breaker/engine/engine_telemetry.rs	Tightens engine telemetry constructor visibility.
crates/seatbelt/src/breaker/engine/engine_fake.rs	Tightens fake engine constructor visibility.
crates/seatbelt/src/breaker/engine/engine_core.rs	Tightens engine core/stat helpers visibility.
crates/ohno/tests/debug_implementation_comparison.rs	Tightens test-local reference types to crate-private.
crates/ohno/src/source.rs	Makes internal enum crate-private.
crates/ohno/src/enrichable.rs	Tightens test-only type visibility.
crates/ohno/src/core.rs	Makes internal boxed core representation crate-private.
crates/ohno_macros/src/utils.rs	Tightens macro helper function visibility.
crates/ohno_macros/src/error_type_attr.rs	Tightens proc-macro entrypoint visibility (internal wiring).
crates/ohno_macros/src/enrich_err/mod.rs	Tightens proc-macro entrypoint + helper visibility.
crates/ohno_macros/src/derive_error/types.rs	Tightens derive internals to crate-private.
crates/ohno_macros/src/derive_error/mod.rs	Stops publicly re-exporting derive internals; makes module items crate-private.
crates/ohno_macros/src/derive_error/from_impls.rs	Tightens derive helper visibility.
crates/ohno_macros/src/derive_error/field_detection.rs	Tightens derive helper visibility.
crates/ohno_macros/src/derive_error/display.rs	Tightens derive helper visibility.
crates/ohno_macros/src/derive_error/constructors.rs	Tightens derive helper visibility.
crates/ohno_macros/src/derive_error/attributes.rs	Tightens derive helper visibility.
crates/multitude/tests/coverage_gaps.rs	Tightens test-only allocator helper visibility.
crates/multitude/tests/common/mod.rs	Tightens shared test helpers/types visibility.
crates/layered/src/testing.rs	Tightens testing helper constructor visibility.
crates/layered/src/intercept.rs	Makes test function crate-private to avoid unreachable public test items.
crates/http_extensions/src/json.rs	Makes test functions crate-private to avoid unreachable public test items.
crates/http_extensions/src/http_utils.rs	Tightens internal helper constructors to crate-private.
crates/fundle/tests/bundle_getters.rs	Adds #[expect(unreachable_pub)] on bundle component types required to remain pub.
crates/fundle/tests/bundle_all_features.rs	Adds #[expect(unreachable_pub)] on bundle component types required to remain pub.
crates/fetch/src/telemetry.rs	Tightens internal telemetry constructor visibility.
crates/fetch/src/pipeline/custom.rs	Tightens internal pipeline factory API visibility.
crates/fetch/src/pipeline/builder.rs	Tightens test-only helpers to crate-private.
crates/fetch/src/handlers/transport.rs	Tightens internal handler constructor visibility.
crates/fetch/src/handlers/dispatch.rs	Tightens internal dispatch constructors visibility.
crates/fetch/src/custom.rs	Tightens internal transport helper methods visibility.
crates/fetch/examples/util/utils.rs	Makes example tracing init crate-private.
crates/fetch/examples/http_client_api_with_templated_uri.rs	Makes example client/types crate-private.
crates/fetch_tls/src/testing.rs	Tightens test-only TLS helpers to crate-private.
crates/fetch_tls/src/rustls.rs	Tightens internal verifier factory helpers to crate-private.
crates/data_privacy/src/redactors/mod.rs	Tightens internal helper function visibility.
crates/data_privacy/src/redaction_engine_inner.rs	Tightens internal engine methods visibility.
crates/data_privacy/examples/employees/logging.rs	Makes example helpers crate-private.
crates/data_privacy/examples/employees/employee.rs	Makes example model types crate-private.
crates/data_privacy_macros_impl/src/taxonomy.rs	Tightens proc-macro helper visibility.
crates/data_privacy_macros_impl/src/classified.rs	Tightens proc-macro helper visibility.
crates/cachet/src/wrapper.rs	Makes internal wrapper type crate-private (remains usable via builder composition).
crates/cachet/src/transform/testing.rs	Tightens test-support codec visibility.
crates/cachet/src/serialize/codec.rs	Tightens internal postcard codec types/ctors visibility.
crates/cachet/src/refresh.rs	Tightens internal refresh helper visibility.
crates/cachet/src/fallback.rs	Makes internal fallback cache wrapper crate-private.
crates/cachet_tier/src/tier.rs	Adds module-level #![expect(unreachable_pub)] due to dynosaur macro interaction.
crates/bytesbuf/src/vec.rs	Tightens internal helper constructor visibility.
crates/bytesbuf/src/span.rs	Tightens internal accessor visibility.
crates/bytesbuf/src/mem/testing/std_alloc_block.rs	Tightens test-only allocator helper visibility.
crates/bytesbuf/src/bytes_compat/from_bytes.rs	Tightens internal helper constructor visibility.
crates/bytesbuf/examples/bb_optimal_path.rs	Makes example-only APIs crate-private.
crates/bytesbuf/examples/bb_has_memory_optimizing.rs	Makes example-only APIs crate-private.
crates/bytesbuf/examples/bb_has_memory_global.rs	Makes example-only APIs crate-private.
crates/bytesbuf/examples/bb_has_memory_forwarding.rs	Makes example-only APIs crate-private.

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