🔑 Implement LNURL-Auth support with error handling, frontend polling, and test coverage

- Added `LnurlAuthController` to handle LNURL authentication flow with signature verification, user creation, and session expiry checks.
- Integrated authentication error polling in `nostrLogin.js`.
- Added `LoginKeyFactory` for testing and database seed purposes.
- Created feature tests (`LnurlAuthTest`) to validate LNURL callback, error responses, and session handling.
- Extended `login.blade.php` with dynamic error handling and reset logic for expired sessions.

database/factories/LoginKeyFactory.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace Database\Factories;
+
+use Illuminate\Database\Eloquent\Factories\Factory;
+
+class LoginKeyFactory extends Factory
+{
+    protected $model = \App\Models\LoginKey::class;
+
+    public function definition(): array
+    {
+        return [
+            'k1' => str()->random(64),
+            'user_id' => \App\Models\User::factory(),
+        ];
+    }
+}