chore: add Gitea service to docker-compose, fix gitignore

- Gitea (postgres-backed) on ports 3000/2222
- Exclude .claude/ dir and *.db from git
- Update CLAUDE.md with Gitea remote info

.gitignore

@@ -24,6 +24,9 @@ frontend/dist/
 .vscode/settings.json
 .idea/
 
+# Claude Code local config (per-machine, not for repo)
+.claude/
+
 # OS
 .DS_Store
 Thumbs.db
@@ -36,7 +39,8 @@ Thumbs.db
 # Runtime data (token store, etc.)
 backend/data/
 
-# Database (PostgreSQL data dir - local only)
+# Database
+*.db
 /pgdata/
 
 # Logs