POST
/auth/login
Authenticate and receive JWT
POST
/create_account
Register a new account
POST
/link_account
Create a linked account
POST
/upload_data
Upload data payload
POST
/sync_data
Sync with merge support
GET
/get_data/:guid
Retrieve data (resolves links)
GET
/health
Health check endpoint
WS
/syncHub
Real-time sync via SignalR