fix: WebSocket wss:// same-origin URL + try/catch to prevent crash on HTTPS

- Change DEFAULT_WS_URL from ws://hostname:3001 to wss://window.location.host
- Wrap WebSocket constructor in try/catch to prevent React crash on connection error
- Fixes white page when opening a project (CADEditor crashed on insecure ws:// from HTTPS page)

frontend/src/crdt/useYjsBinding.ts

@@ -41,7 +41,7 @@ export interface UseYjsBindingResult {
   clearSelection: () => void;
 }
 
-const DEFAULT_WS_URL = `ws://${window.location.hostname}:3001`;
+const DEFAULT_WS_URL = `wss://${window.location.host}`;
 
 export function useYjsBinding(opts: UseYjsBindingOptions): UseYjsBindingResult {
   const { docName, wsUrl = DEFAULT_WS_URL, userId, userName, userColor, enabled = true } = opts;