Expand Link app with analytics, settings, and custom domains.

Add Bitly-style branded domain support via Ladill Domains SSL API,
account analytics dashboard, settings page with default domain picker,
and fix SSO/dashboard issues from QR Plus template leftovers.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/Http/Controllers/Api/SslCallbackController.php

@@ -0,0 +1,38 @@
+<?php
+
+namespace App\Http\Controllers\Api;
+
+use App\Http\Controllers\Controller;
+use App\Services\CustomDomain\LinkCustomDomainService;
+use Illuminate\Http\JsonResponse;
+use Illuminate\Http\Request;
+
+class SslCallbackController extends Controller
+{
+    public function __invoke(Request $request, LinkCustomDomainService $service): JsonResponse
+    {
+        $secret = (string) config('customdomain.callback_secret');
+        $body = $request->getContent();
+        $signature = (string) $request->header('X-Ladill-Signature', '');
+
+        if ($secret === '' || ! hash_equals(hash_hmac('sha256', $body, $secret), $signature)) {
+            return response()->json(['error' => 'Invalid signature.'], 401);
+        }
+
+        $payload = json_decode($body, true);
+        $data = (array) ($payload['data'] ?? []);
+        $host = (string) ($data['host'] ?? '');
+        if ($host === '') {
+            return response()->json(['error' => 'Missing host.'], 422);
+        }
+
+        $service->applyCallback(
+            $host,
+            (string) ($data['status'] ?? 'failed'),
+            $data['expires_at'] ?? null,
+            $data['last_error'] ?? null,
+        );
+
+        return response()->json(['status' => 'ok']);
+    }
+}