Remove HANDOFF.md from repository

Local planning document, not needed in shared repo.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: pittolive

.gitignore

@@ -21,3 +21,8 @@ Thumbs.db
 .tmp/
 tmp/
 temp/
+
+# Local planning / handoff docs (not for repo)
+SPRINT_PLAN.md
+HANDOFF.md
+GITHUB_CONFIG_CHECK.md