chore: add copyright header guidance to CLAUDE.md (#12541)

This PR adds a "Copyright Headers" section to `.claude/CLAUDE.md`
instructing Claude to:
- Always use `date +%Y` for the copyright year instead of relying on
memory
- Match the copyright holder to what the author uses in other recent
files in the repo
- Skip copyright headers for test files in `tests/`

🤖 Prepared with Claude Code

---------

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", "Amazon.com, Inc. or its affiliates").
+
+Test files (in `tests/`) do not need copyright headers.