Add comprehensive API documentation to Cloudron setup instructions

- Added detailed API endpoint information in SETUP-INSTRUCTIONS.md
- Documented API usage with Ente CLI
- Enhanced routing configuration for auth/cast/accounts apps
- Updated to version 0.1.64

CloudronManifest.json

@@ -7,7 +7,7 @@
   "contactEmail": "contact@ente.io",
   "tagline": "Open Source End-to-End Encrypted Photos & Authentication",
   "upstreamVersion": "1.0.0",
-  "version": "0.1.62",
+  "version": "0.1.64",
   "healthCheckPath": "/ping",
   "httpPort": 3080,
   "memoryLimit": 1073741824,