fix(core): the unknown-tool error links a broken manifest by its declared name

[Max17190]

Why

Round-7 contract audit (F9). The unknown-tool error's "exists but did NOT load" link matched broken files by FILE STEM, while the registry keys tools on the DECLARED name, and the spec's own <name>.toml placeholder invites the hyphen-file/underscore-tool split. A model calling todo_scan after its todo-scan.toml broke got a bare unknown tool and concluded the file was never written. The refreeze receipt covers the writing turn; the gap was the resumed or externally-edited case.

Stacked on #248, which introduced the broken_tools (path, occupied name) list this match keys on.

Summary

The broken-file link tries the occupied-name match first (declared name, stem fallback: the registry's own collision key), then falls back to the existing stem and SKILL.md matchers, which still serve manifest-restored registries whose broken_tools is empty.

Test Plan

• a_broken_manifest_is_named_when_its_declared_name_differs_from_its_stem: hyphen file declaring an underscore name, broken; calling the declared name returns the did-NOT-load error naming the file. Red against a disabled name-match (verified).
• Full workspace green (exit 0), clippy zero warnings.

Greptile Summary

The registry now identifies unavailable tools by their declared manifest name and reports the project-level manifest when it overrides an invalid global manifest. Focused coverage confirms both diagnostic paths behave as intended.

Confidence Score: 5/5

No blocking failure remains; the project override diagnostic behaves correctly.

The focused checks exercised both invalid-manifest resolution paths and confirmed that each reports the intended manifest.

T-Rex Logs

What T-Rex did

• Ran the two focused tests for broken project tool manifests and broken manifest naming, and the results confirm that a broken project override is named ahead of an invalid global manifest and that a broken manifest is found through its declared tool name.
• The regression runner captured the exact commands, working directory, and exit codes for the tests, and noted that no repository source files were modified while only executable proof artifacts were added.

_{Ran code and verified through T-Rex}

_{Reviews (3): Last reviewed commit: "fix(core): a doubly broken name is linke..." | Re-trigger Greptile}