Migrate backend from Lovable Cloud to own Supabase (EDU project)

- Point .env + supabase/config.toml at EDU (qgmcpounpkgsjlwosjdi)
- Replace Lovable Google-OAuth shim with native supabase.auth.signInWithOAuth
- Remove src/integrations/lovable and @lovable.dev/cloud-auth-js dependency
- Drop .lovable metadata; gitignore supabase/.temp

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/routes/auth.tsx

@@ -2,7 +2,6 @@ import { createFileRoute, useNavigate } from "@tanstack/react-router";
 import { useState } from "react";
 import { z } from "zod";
 import { supabase } from "@/integrations/supabase/client";
-import { lovable } from "@/integrations/lovable";
 import { Button } from "@/components/ui/button";
 import { Input } from "@/components/ui/input";
 import { Label } from "@/components/ui/label";
@@ -51,9 +50,14 @@ function AuthPage() {
   };
 
   const onGoogle = async () => {
-    const res = await lovable.auth.signInWithOAuth("google", { redirect_uri: window.location.origin });
-    if (res.error) toast.error(res.error.message ?? "Google sign-in failed");
-    else if (!res.redirected) navigate({ to: "/dashboard" });
+    // Native Supabase OAuth: redirects the browser to Google, then back to
+    // redirectTo. supabase-js (detectSessionInUrl) restores the session on
+    // return, and useAuth's onAuthStateChange picks it up.
+    const { error } = await supabase.auth.signInWithOAuth({
+      provider: "google",
+      options: { redirectTo: `${window.location.origin}/dashboard` },
+    });
+    if (error) toast.error(error.message ?? "Google sign-in failed");
   };
 
   return (