fix: correct git log format and resolve symlinks in year update cache

[CreatorHead]

🛠️ Description

Two bugs were introduced in #191 (42a6ce3) that caused copyright year updates to never be applied when running copywrite headers.

Bug 1 — Wrong git log format string (buildRepositoryCache)

buildRepositoryCache used --format=format:%ad which outputs bare years (e.g. 2026). However, the parser expected lines prefixed with __CW_YEAR__= to distinguish year lines from filename lines. Since the prefix was never emitted, currentYear stayed 0, the cache was always empty, and lastCommitYear was always 0 for every file. This meant the condition lastCommitYear > info.EndYear was never true, so end years were never bumped.

Fix: change format string to --format=format:__CW_YEAR__=%ad to match what the parser expects.

Bug 2 — Symlink path mismatch on macOS (getFileLastCommitYear)

getFileLastCommitYear computed the relative path via filepath.Rel(repoRoot, absPath). On macOS, tmp is a symlink to tmp. git rev-parse --show-toplevel (used to get repoRoot) resolves the real path (e.g. /private/tmp/repo), while filepath.Abs preserves the symlink path (e.g. /tmp/repo). This mismatch caused filepath.Rel to produce a wrong relative path, resulting in a cache miss on every file.

Fix: call filepath.EvalSymlinks on absPath before computing the relative path. This is a no-op on Linux and Windows where symlinks are not involved.

🔗 External Links

• Regression introduced in improve performance by only looking up git information once #191 / 42a6ce3

👍 Definition of Done

• New functionality works?
• Tests added?

🤔 Can be merged upon approval?

✅

PCI review checklist

• I have documented a clear reason for, and description of, the change I am making.

• If applicable, I've documented a plan to revert these changes if they require more than reverting the pull request.

  These changes are limited to update.go. To revert, simply revert this PR or cherry-pick the fix from 42a6ce3 with the corrected format string and symlink resolution.

• If applicable, I've documented the impact of any changes to security controls.

  No security controls are affected. This is a bug fix for git log parsing and file path resolution in the copyright year update logic.

[mohanmanikanta2299]

LGTM.