Update Node-RED configuration and documentation for room management

- Added node-red/config_files/flows_cred.json to .gitignore to prevent committing sensitive credentials.
- Updated documentation references to the new location of room-config.js in node-red/config_files/ for clarity.
- Removed the obsolete room-config.js file, centralizing configuration management.

This update enhances security and improves the organization of Node-RED configuration files, ensuring better management of room settings.

.gitignore

@@ -43,6 +43,9 @@ temp/
 # Node modules (if any)
 node_modules/
 
+# Node-RED: encrypted credentials (pull from server for backup; do not commit)
+node-red/config_files/flows_cred.json
+
 # Python
 __pycache__/
 *.pyc