fix(calendar): remove setState call from render in isFormValid

validateUrl() calls setUrlError() — calling it during render triggers
React error #301 (cannot update component while rendering). Remove it
from the isFormValid computation; onChange/onBlur already keep urlError
in sync so !urlError is sufficient.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/web/src/components/settings/calendar-source-form.tsx

@@ -94,13 +94,14 @@ export function CalendarSourceForm({
     }
   }, [t]);
 
-  // Form is valid when name, type, and url are filled and url is https
+  // Form is valid when name, type, and url are filled and url passed validation.
+  // Do NOT call validateUrl here — it calls setUrlError which is a state update
+  // during render (React error #301). onChange/onBlur already set urlError.
   const isFormValid =
     name.trim() !== '' &&
     type !== '' &&
     url.trim() !== '' &&
-    !urlError &&
-    validateUrl(url);
+    !urlError;
 
   const handleSubmit = useCallback(
     async (e: React.FormEvent) => {