fix: repository detection from subdirectories

[BlackPool25]

Summary

Fixes brittle repository detection when running lrc hooks install --local and lrc hooks uninstall --local from nested subdirectories of a Git repository.

• Renamed and updated check: Renamed IsGitRepositoryCurrentDir → IsGitRepository in gitops/config.go. Replaced os.Stat(".git") (only works at repo root) with git rev-parse --is-inside-work-tree (traverses parent dirs correctly).
• Updated callsite: Updated isGitRepository() in internal/appcore/hooks_management.go to call the renamed function.
• E2E coverage: Added subdirectory integration tests to tests/worktree-hooks.sh.

Root Cause

IsGitRepositoryCurrentDir() used os.Stat(".git") which resolves relative to the current working directory. When invoked from a subdirectory, the .git entry is not found even though CWD is inside a valid Git worktree.

Changes Made

1. gitops/config.go — Replace function body, rename, remove unused "os" import
2. internal/appcore/hooks_management.go — Update delegate call
3. tests/worktree-hooks.sh — Add "Local Hook Management In Subdirectories" test section

Testing

• make test-go — All Go packages pass
• make test-hooks-worktree — All 32 tests pass (including 10 new subdirectory tests)

Checklist

• This PR fulfills an agreed issue.
• I kept the change narrow and scoped.
• I ran the most specific relevant validation and described it above.
• If I changed behavior, I called that out clearly in this PR.
• If I touched UI, I attached a GIF or video walkthrough. This is required. (No UI changes)
• If I changed storage/ responsibilities, I updated storage/storage_status.md and ran make check-status-doc. (No storage changes)
• If I changed network/ responsibilities, I updated network/network_status.md and ran make check-status-doc. (No network changes)
• If this change touches security, disclosure flow, credentials, storage, network behavior, or remote data handling, I reviewed SECURITY.md and updated related documentation if needed. (No security-sensitive changes)

Linked Issue

Fixes #128

Notes For Reviewers

The new E2E tests in tests/worktree-hooks.sh under "Local Hook Management In Subdirectories" verify install, status, and uninstall from a nested subdirectory.