fix(storage): ignore invalid ancestor Git markers

[faga295]

Summary

Ignore structurally invalid .git entries in strict ancestors when classifying a selected folder, while preserving fail-closed behavior for a malformed .git entry in the selected folder itself. Valid Git directories, gitdir: indirection files, repositories, and linked worktrees continue to resolve normally.

Add regression coverage for Project Catalog classification and workspace identity marker publication.

Fixes #4806

Verification

• npm --workspace @maka/storage run build
• npm --workspace @maka/storage run typecheck
• npm --workspace @maka/storage run test:dist — 1,112 passed, 8 skipped, 0 failed
• npx biome check packages/storage/src/git-entry.ts packages/storage/src/__tests__/project-catalog.test.ts packages/storage/src/__tests__/workspace-identity.test.ts
• npm run check:asf-headers
• Verified the affected real-world folder now resolves with kind: 'folder'

AI use

Select exactly one:

• No generative tool made a substantive contribution
• Generative tooling made a substantive contribution

Tool(s) and scope: OpenAI Codex — root-cause analysis, implementation, regression tests, verification, and PR drafting.

Checklist

• Tests cover the change and fail without it
• Lint, format, typecheck and the affected suites pass locally

Does this PR entail a change in behavior?

• Yes — described under Summary above
• No