feat(api): add AI text-to-deck generation, wallet deposit structure, and profile/notification endpoints

Fills the gaps between the admin panel screens and the backend: a full
free-text + slide-count + language -> AI-generated presentation flow with
new slide-cloning logic in TemplateFillService, a "my presentations" list
endpoint, a swappable payment-gateway structure for wallet top-ups (fake
driver for now), and avatar upload / public-profile toggle / account
deletion / password change / notification preference endpoints.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/Services/Payments/FakePaymentGateway.php

@@ -0,0 +1,35 @@
+<?php
+
+namespace App\Services\Payments;
+
+use App\Contracts\PaymentGateway;
+use App\Models\WalletDeposit;
+use Illuminate\Support\Str;
+
+/**
+ * Stand-in gateway used until a real provider (e.g. ZarinPal, Zibal) is wired up.
+ * It simulates an instant-success redirect straight to the callback route, so the
+ * full initiate -> redirect -> callback -> credit flow is testable end-to-end
+ * without any external credentials. Swap the PaymentGateway binding in
+ * AppServiceProvider to replace it with a real driver.
+ */
+class FakePaymentGateway implements PaymentGateway
+{
+    public function initiate(WalletDeposit $deposit): string
+    {
+        $deposit->update(['reference_id' => (string) Str::uuid()]);
+
+        return route('api.wallet.deposits.callback', [
+            'deposit' => $deposit->id,
+            'reference_id' => $deposit->reference_id,
+            'status' => 'success',
+        ]);
+    }
+
+    public function verify(WalletDeposit $deposit, array $callbackPayload): bool
+    {
+        return $deposit->reference_id !== null
+            && ($callbackPayload['reference_id'] ?? null) === $deposit->reference_id
+            && ($callbackPayload['status'] ?? null) === 'success';
+    }
+}