fix(hooks): bound worktree discovery instead of an open git walk

[ScriptedAlchemy]

Summary

• Hook plans, branch authorization, and the ledger worktree lookup use bounded repository discovery.
• A cancelled or expired probe is unavailable. It is not treated as the main checkout.

Test plan

• cargo test -p tracedecay-mcp --lib hook_events::tests -- --test-threads=1 passed, 21 tests (cc-23359)
• cargo check -p tracedecay --lib passed for the ledger caller (cc-23356)

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Latest commit: 97f97d7

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[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-17T16:32:01.522105Z	97f97d7	PR opened

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