fix(settings): update cache immediately on save instead of invalidating

Using setQueryData with the PATCH response means jira_token_set is
reflected in the UI instantly — no extra GET round-trip that could
leave the badge stale.

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

frontend/src/pages/SettingsPage.tsx

@@ -834,10 +834,11 @@ function ProfileSection() {
 
   const saveMut = useMutation({
     mutationFn: updateMyPreferences,
-    onSuccess: () => {
-      qc.invalidateQueries({ queryKey: ["me-prefs"] });
+    onSuccess: (updatedMe) => {
+      // Update cache immediately with the response — no extra round-trip needed
+      qc.setQueryData(["me-prefs"], updatedMe);
       setDirty(false);
-      setJiraApiToken(""); // clear token field after save — it's now persisted
+      setJiraApiToken(""); // clear token field after save — it's persisted
       setToast({ msg: "Profile settings saved", type: "success" });
     },
     onError: () => setToast({ msg: "Failed to save", type: "error" }),