fix: Prevent nodemon restarts during policy creation

- Move temp directory outside app folder to /tmp/minio-webui-temp
- Add nodemon.json to ignore temp, logs, and node_modules
- Add TEMP_DIR environment variable configuration
- Add cleanup routine for old temporary policy files (>1 hour)
- Update both dev and production Dockerfiles
- Update docker-compose configurations

This fixes the 500 error during QuickStartWizard policy creation
caused by nodemon restarting when temporary files were created.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

backend/nodemon.json

@@ -0,0 +1,14 @@
+{
+  "watch": ["src"],
+  "ext": "js,json",
+  "ignore": [
+    "src/**/*.spec.js",
+    "node_modules",
+    "logs",
+    "temp",
+    "*.log",
+    "*.tmp",
+    "*.temp"
+  ],
+  "delay": "1000"
+}