fix(core): metadata source walk skips cache dirs and vanished files

[Aymericr]

What does this PR do?

This fixes the quality failure that #923 introduced on main at a9c1d4561. The failure also reproduced on a rerun.

Cause: reference-inventory.test.ts walks every editor source file to find the metadata keys it uses. At the same time, history.test.ts creates and deletes .turbo/history-*/probe.ts. When a file the walk has already listed is deleted before it is stat'ed or read, the walk throws ENOENT.

Changes:

• Walk extracted. The walk now lives in contracts/metadata-scan.ts as scanMetadataSources. It takes an injectable fs so a test can reproduce the race. This file stays test and tooling only, excluded from the package build.
• Build and cache dirs skipped. The walk now skips node_modules, dist, build, out, coverage, __fixtures__ and every dot-directory (.turbo, .next, …).
• Deleted files tolerated. An ENOENT from readdir, stat or read is treated as a file that vanished mid-walk and is skipped. Any other error still throws.

Commits:

1. 79909befa adds the reproducing test. It deletes a listed file between readdir and stat, and plants a .turbo/history-1/probe.ts. On that commit the test fails with ENOENT: … stat …/vanishing.ts.
2. The second commit is the fix; the same test now passes.

How to test

1. bun run --cwd packages/core test: 2955 pass, 0 fail.
2. bun run --cwd packages/core check-types: clean.
3. bun run check: clean.

Screenshots / screen recording

Not applicable: tests only.

Checklist

• I've tested this locally (core tests; no bun dev surface)
• My code follows the existing code style (run bun check to verify)
• I've updated relevant documentation (if applicable)
• This PR targets the main branch

🤖 Generated with Claude Code

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Note

Low Risk
Changes are limited to contract/test tooling in metadata-scan.ts and inventory tests; no runtime editor or package build surface.

Overview
Fixes flaky quality failures when reference-inventory.test.ts walks editor sources while other suites delete files under .turbo.

The inline source-tree walk is replaced by scanMetadataSources in metadata-scan.ts, which maps metadata keys to the first source file that uses them. The walk now ignores build/cache/dependency paths (dist, build, out, coverage, etc.) and all dot-directories (e.g. .turbo), and treats ENOENT on readdir/stat/read as a file that disappeared mid-scan instead of throwing. Filesystem access is injectable via ScanFs so tests can simulate the race.

reference-inventory.test.ts uses the shared scanner for METADATA_KEYS and adds a test that deletes a listed file between readdir and stat while ensuring keys under .turbo are not picked up.

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[pascal]

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Error id: daf35de7-e1eb-4dc3-9bdc-d90943e94c50