Quick wins batch

[maxholman]

Quick wins batch

Scope

A grab-bag of small, self-contained improvements from TODO.md — code quality,
website copy, and minor UX fixes. Each item is independent.

1. Metrics field visibility

Make the seven AtomicU64 fields in crates/core/src/control/metrics.rs
private. The existing inc_*/dec_* methods are the correct API surface.

Impl notes: Only two call sites read fields directly — both in
crates/core/src/control/handler.rs: handle_stats() (line ~101) and
metrics() (line ~286). Add a snapshot/read method to Metrics and use it
from those two call sites.

2. TryFrom<ProtoNodeRole> error type

Replace type Error = String in crates/core/src/types.rs (line ~28) with a
proper NodeRoleError enum. Only one error case exists: RoleUnknown. A
design is already sketched in docs/tasks/10-type-system-improvements.md.

3. ExitNodeResponse construction boilerplate

Add a constructor to ExitNodeResponse (protobuf-generated, defined in
crates/wire/proto/data.proto lines 136-146). The pair: Some(…), response: Some(…) pattern is repeated ~20 times across crates/core/src/exit/orchestrator.rs
and crates/exit-adapter/src/adapter.rs. A simple fn new(pair: Option<SocketAddressPair>, response: Response) -> Self that wraps response
in Some(…) covers all cases. One test uses ..Default::default() — leave
that alone.

4. Website stale benchmark claim

website/src/content/docs/index.mdoc line ~30 claims "2.4 Gbps" but the
actual benchmark table in benchmarks.mdoc shows TCP maxing at ~1.5 Gbps.
Replace with "multi-gigabit" or similar. Also check the packet-loss claim on
line ~32 ("7.7 Mbps" / "17 Mbps") against the benchmark data.

6. Fix "ping the daemon" description

Two locations:

• crates/cli/src/repl.rs line ~196: "ping [<peer>]\tPing the daemon or a peer"
• crates/cli/src/cli.rs line ~31: /// Ping the daemon or a peer.

The daemon-ping path (ipc.rs line ~215) returns status info (uptime, version,
role) — that's the info command, not ping. Peer ping returns "not yet
implemented". Fix the help text to say "Ping a peer". No-arg behavior should
auto-select the sole connected peer (the protobuf PingRequest.peer field
already supports empty = auto-select). If zero or multiple peers are connected,
return a clear error.

7. Audit #[allow(clippy::...)] suppressions

33 instances total. Categories:

• Auto-generated code (5): wire/src/{control,data,management}.rs,
  cli/src/version.rs, daemon/src/lib.rs — all suppress doc_markdown/
  must_use_candidate/needless_raw_string_hashes on include!() blocks.
  Already commented or self-evident. Leave as-is.
• too_many_lines (7): All marked // refactor candidate. Leave as-is
  (out of scope for this task).
• cast_possible_truncation (6): Port u32→u16 casts from protobuf,
  millis as u64, ICMP ident. All safe in context. Add brief comments.
• cast_precision_loss (2): usize as f64 for throughput display. Safe.
  Add brief comments.
• missing_errors_doc (2): Crate-level in core and exit-adapter.
  Core already has a comment. Add comment to exit-adapter.
• module_inception (2): client/mod.rs and server/mod.rs. Intentional
  structure. Add brief comments.
• result_large_err (2): client/ws/mod.rs. Add comments explaining
  the error type.
• needless_pass_by_value (1): entry-stack constructor. Already
  commented. Leave as-is.
• struct_excessive_bools (1): CLI flags struct. Already commented.
  Leave as-is.
• socket_set.rs crate-level cast_possible_truncation (1): Blanket
  suppression. Consider narrowing to specific sites or add a module-level
  comment.

8. Parameter naming consistency

12 renames across 4 files where minority impls diverge from the established
convention:

pair → set (ExitAdapter trait / mock):

• crates/core/src/exit/net/adapter.rs:116 — tcp_listen(pair → set
• crates/core/tests/mock_exit.rs:27 — tcp_close(pair → set
• crates/core/tests/mock_exit.rs:54 — tcp_listen(_pair → _set
• crates/core/tests/mock_exit.rs:68 — udp_send(_pair → _set
• crates/core/tests/mock_exit.rs:77 — icmp_session(_pair → _set
• crates/core/tests/mock_exit.rs:85 — udp_recv_session(_pair → _set
• crates/core/tests/mock_exit.rs:92 — tcp_recv_session(_pair → _set

buf → data (ExitAdapter::tcp_send trait def):

• crates/core/src/exit/net/adapter.rs:103 — buf → data

dst_addr → dest (RxSession::send impls):

• crates/exit-adapter/src/sessions/tcp.rs:31 — _dst_addr → _dest
• crates/exit-adapter/src/sessions/icmp.rs:88 — dst_addr → dest

args → config (Client::try_new QUIC impl):

• crates/core/src/client/quic/mod.rs:70 — args → config

_ocsp → _ocsp_response (ServerCertVerifier):

• crates/core/src/tls/verifiers.rs:23 — _ocsp → _ocsp_response

Out of scope

• Anything architectural (ConnectionManager decomposition, arc-swap, etc.)
• New features (DNS transport, shell command, etc.)
• Performance work (buffer pooling, lock contention)
• Anything requiring new dependencies

Why

Low-risk improvements that tighten the type system, reduce boilerplate, fix
stale docs, and clean up suppressions. All quick to implement and review.

Notes

• Items are independent — can be done in any order
• Each item should be its own commit on the branch
• Run just check after each item