Fix duplicate isReadOnly declaration blocking builds

Fixed a duplicate isReadOnly variable declaration in TriggerForm.tsx
(lines 37 and 46) that was causing esbuild to fail with error:
"The symbol 'isReadOnly' has already been declared"

This was preventing Phoenix from rebuilding assets, blocking all
development work on the collaborative editor.

Author: elias-ba

assets/js/collaborative-editor/components/inspector/TriggerForm.tsx

@@ -43,7 +43,6 @@ export function TriggerForm({ trigger }: TriggerFormProps) {
   const sessionContext = useSessionContext();
   const { provider } = useSession();
   const channel = provider?.channel;
-  const { isReadOnly } = useWorkflowReadOnly();
 
   // Get active trigger auth methods from workflow store
   const activeTriggerAuthMethods = useWorkflowState(