feat(railpack): add config merging, beta badge, and nodejs seeder example

- Implement railpack.json + generated config deep merging logic in
  ApplicationDeploymentJob with JSON validation and assoc array checks
- Label Railpack as "Beta" in all build pack selectors and show a
  visible beta badge when railpack is selected in new-app forms
- Add railpack-nodejs Fastify example to ApplicationSeeder
- Add ApplicationSeederTest and ApplicationDeploymentRailpackConfigTest
  covering config merge behavior and seeder correctness

tests/Feature/ApplicationSeederTest.php

@@ -0,0 +1,51 @@
+<?php
+
+use App\Models\Application;
+use Database\Seeders\ApplicationSeeder;
+use Database\Seeders\GithubAppSeeder;
+use Database\Seeders\PrivateKeySeeder;
+use Database\Seeders\ProjectSeeder;
+use Database\Seeders\ServerSeeder;
+use Database\Seeders\StandaloneDockerSeeder;
+use Database\Seeders\TeamSeeder;
+use Database\Seeders\UserSeeder;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+
+uses(RefreshDatabase::class);
+
+it('seeds a railpack nodejs fastify example alongside the existing nixpacks example', function () {
+    $this->seed([
+        UserSeeder::class,
+        TeamSeeder::class,
+        PrivateKeySeeder::class,
+        ServerSeeder::class,
+        ProjectSeeder::class,
+        StandaloneDockerSeeder::class,
+        GithubAppSeeder::class,
+        ApplicationSeeder::class,
+    ]);
+
+    $nixpacksExample = Application::where('uuid', 'nodejs')->first();
+    $railpackExample = Application::where('uuid', 'railpack-nodejs')->first();
+
+    expect($nixpacksExample)
+        ->not->toBeNull()
+        ->and($nixpacksExample->name)->toBe('NodeJS Fastify Example')
+        ->and($nixpacksExample->build_pack)->toBe('nixpacks')
+        ->and($nixpacksExample->base_directory)->toBe('/nodejs')
+        ->and($nixpacksExample->ports_exposes)->toBe('3000');
+
+    expect($railpackExample)
+        ->not->toBeNull()
+        ->and($railpackExample->name)->toBe('Railpack NodeJS Fastify Example')
+        ->and($railpackExample->fqdn)->toBe('http://railpack-nodejs.127.0.0.1.sslip.io')
+        ->and($railpackExample->repository_project_id)->toBe(603035348)
+        ->and($railpackExample->git_repository)->toBe('coollabsio/coolify-examples')
+        ->and($railpackExample->git_branch)->toBe('v4.x')
+        ->and($railpackExample->base_directory)->toBe('/nodejs')
+        ->and($railpackExample->build_pack)->toBe('railpack')
+        ->and($railpackExample->ports_exposes)->toBe('3000')
+        ->and($railpackExample->environment_id)->toBe(1)
+        ->and($railpackExample->destination_id)->toBe(0)
+        ->and($railpackExample->source_id)->toBe(1);
+});