chore(docker): improve init script robustness and ignore db-data

- Add file existence checks before iterating schema directories
- Add proper quoting for file paths
- Add completion message
- Ignore docker/db-data/ (PostgreSQL runtime data)

.gitignore

@@ -18,4 +18,7 @@ config.json
 # Logs
 logs/
 
-.env
+.env
+
+# Docker
+docker/db-data/