feat: add password reset email

app/(app)/(auth)/layout.tsx

@@ -1,13 +1,47 @@
+"use client";
+
 /**
  * Shared layout for the auth pages (login, signup, forgot-password,
  * reset-password). Provides the centered card frame so each page only
  * has to render its own form.
+ *
+ * Also gates the routes: a signed-in user landing on any /login, /signup,
+ * etc. URL is bounced to /u/me (or the `next` query param if present).
+ * The check happens client-side because auth state lives in
+ * AuthProvider — there's no server-side cookie inspection here yet, and
+ * the redirect is purely cosmetic (logged-in users don't gain anything
+ * from re-seeing these forms, and signing in over an existing session
+ * would just no-op).
  */
+
+import { useEffect } from "react";
+import { useRouter, useSearchParams } from "next/navigation";
+import { useAuth } from "@/components/auth/auth-provider";
+
 export default function AuthLayout({
   children,
 }: {
   children: React.ReactNode;
 }) {
+  const { user, loading } = useAuth();
+  const router = useRouter();
+  const params = useSearchParams();
+
+  useEffect(() => {
+    if (loading || !user) return;
+    const next = params.get("next");
+    router.replace(next && next.startsWith("/") ? next : "/u/me");
+  }, [loading, user, router, params]);
+
+  // Don't flash the form for an instant before the redirect fires.
+  if (!loading && user) {
+    return (
+      <main className="flex items-center justify-center px-4 py-12 min-h-[90vh]">
+        <p className="text-sm text-muted-foreground">Redirecting…</p>
+      </main>
+    );
+  }
+
   return (
     <main className="flex items-center justify-center px-4 py-12 min-h-[90vh]">
       <div className="w-full max-w-md">{children}</div>