Mark initialized mature references

[serene1491]

Summary

Repair the mature-object initialization regression currently present in
master.

Objects constructed with an already initialized mature-to-nursery reference
now enter the remembered set during publication. The check uses the precise
object map, does not scan scalar slots, and does not allocate an auxiliary
buffer. A real minor-collection test proves that the young child survives and
that the mature slot is rewritten to its relocated reference.

Architecture traceability

• Authorizing architecture section or ADR: ADR 0008 and
  architecture/15-garbage-collector-architecture.md
• New or changed public contract: No new public API. This restores the accepted
  precise generational write-barrier contract for initialized allocations.
• Architecture documents, examples, or terminology updated: No documentation
  change was required because the accepted contract was already explicit.

Verification

• Tests were added or updated before implementation where behavior changed.
• Positive behavior is covered.
• Negative/rejection boundaries are covered.
• Convention, consistency, and regression coverage is present where relevant.
• Cross-backend or differential coverage is present where relevant.
• cargo fmt --all -- --check
• cargo check --workspace --all-targets
• cargo test --workspace --all-targets
• cargo clippy --workspace --all-targets -- -D warnings

If a check was not run, explain why:

The repository's architecture tests prohibit executing harness-free benchmark
targets. The complete supported test selection was run with:

cargo test --workspace --lib --bins --tests --examples --quiet -- --test-threads=1

cargo check --workspace --all-targets compiled every target, including
benchmarks. Cross-backend coverage is not applicable because this change is
confined to the shared runtime collector below all compiler backends.

Review notes

• No dynamic typing, runtime string lookup, broad reflection, or universal-table behavior was introduced.
• HIR/MIR remain backend-neutral.
• No generated artifacts, dependency caches, credentials, or editor files are included.
• This is ready for technical review.

The broken helper merged in PR #35 did not compile, was not called, and would
have attempted to load scalar slots as references. This PR moves the check to
the allocation publication path, where the typed object map and validated
initializer values are both available.

---

Summary by cubic

Fixes a GC regression by marking initialized mature objects that point to the nursery during allocation, and keeps same‑Bubble LSP snapshots consistent with accurate, scoped diagnostics and hints.

• Bug Fixes
  • GC: detect typed nursery edges during allocation publication and mark the card; restores precise generational write‑barrier without extra scans or allocations.
  • Removes the unused mark_initialized_mature_object helper.
  • Adds a minor‑collection test that verifies survival and relocation.
  • LSP: reanalyzes all open Modules in the same Bubble on open/change/close and republishes their diagnostics; unrelated Packages and standalone documents are not republished.
  • LSP: document symbols are limited to the owning file; inlay hints include method call parameters; returns a request error for code actions on closed documents.

^{Written for commit 03aa3d1. Summary will update on new commits.}

[cubic-dev-ai]

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