style(frontend): Prettier config + one-time repo-wide format pass

Prettier 3 (pinned), printWidth 100, double quotes — chosen to match the existing
hand-formatting and minimise reflow. This commit is ONLY the mechanical format pass
(`prettier --write`) plus the config/ignore/scripts, isolated so it never pollutes a
feature diff. Verified behaviour-neutral: typecheck, eslint (0 errors), and vitest
all green before and after. See .git-blame-ignore-revs — `git blame` skips this sha.

frontend/src/components/KeyGate.tsx

@@ -11,7 +11,11 @@ import * as e2ee from "../lib/e2ee";
 export default function KeyGate({ meId, compact = false }: { meId: number; compact?: boolean }) {
   const { t } = useTranslation();
   const qc = useQueryClient();
-  const keyQ = useQuery({ queryKey: ["message-key"], queryFn: api.messageMyKey, staleTime: 60_000 });
+  const keyQ = useQuery({
+    queryKey: ["message-key"],
+    queryFn: api.messageMyKey,
+    staleTime: 60_000,
+  });
   const configured = keyQ.data?.configured ?? false;
 
   const [pass, setPass] = useState("");
@@ -39,15 +43,22 @@ export default function KeyGate({ meId, compact = false }: { meId: number; compa
     }
   }
 
-  if (keyQ.isLoading) return <div className="p-6 text-center text-muted text-sm">{t("common.loading")}</div>;
+  if (keyQ.isLoading)
+    return <div className="p-6 text-center text-muted text-sm">{t("common.loading")}</div>;
 
   return (
     <div className={`glass rounded-2xl space-y-3 ${compact ? "p-3" : "p-4"}`}>
       <div className="flex items-center gap-2">
         <ShieldCheck className="w-5 h-5 text-accent shrink-0" />
-        <div className="font-semibold text-sm">{configured ? t("messages.unlockTitle") : t("messages.setupTitle")}</div>
+        <div className="font-semibold text-sm">
+          {configured ? t("messages.unlockTitle") : t("messages.setupTitle")}
+        </div>
       </div>
-      {!compact && <p className="text-sm text-muted">{configured ? t("messages.unlockBody") : t("messages.setupBody")}</p>}
+      {!compact && (
+        <p className="text-sm text-muted">
+          {configured ? t("messages.unlockBody") : t("messages.setupBody")}
+        </p>
+      )}
       <input
         type="password"
         value={pass}