chore: add copyright header guidance to CLAUDE.md

This adds prompting to ensure new files get correct copyright headers
with the current year (via `date`, not from memory) and the right
copyright holder (matched from other files by the same author).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: kim-em

.claude/CLAUDE.md

@@ -87,3 +87,9 @@ If you're unsure which label applies, it's fine to omit the label and let review
 ## CI Log Retrieval
 
 When CI jobs fail, investigate immediately - don't wait for other jobs to complete. Individual job logs are often available even while other jobs are still running. Try `gh run view <run-id> --log` or `gh run view <run-id> --log-failed`, or use `gh run view <run-id> --job=<job-id>` to target the specific failed job. Sleeping is fine when asked to monitor CI and no failures exist yet, but once any job fails, investigate that failure immediately.
+
+## Copyright Headers
+
+New files require a copyright header. To get the year right, always run `date +%Y` rather than relying on memory. The copyright holder should be the author or their current employer — check other recent files by the same author in the repository to determine the correct entity (e.g., "Lean FRO, LLC", "Microsoft Corporation"). Do not guess; match what the author uses elsewhere.
+
+Test files (in `tests/`) do not need copyright headers.