fix(application-source): support localhost key with id=0

Previously, the view checked $privateKeyId with ! operator, which
incorrectly treats 0 (localhost key) as falsy. Changed to explicit
is_null() checks to distinguish between null (no key) and 0 (localhost).
Added test coverage for both cases.

resources/views/livewire/project/application/source.blade.php

@@ -28,7 +28,7 @@
         <div class="pb-4">Code source of your application.</div>
 
         <div class="flex flex-col gap-2">
-            @if (!$privateKeyId)
+            @if (is_null($privateKeyId))
                 <div>Currently connected source: <span
                         class="font-bold text-warning">{{ data_get($application, 'source.name', 'No source connected') }}</span>
                 </div>
@@ -44,7 +44,7 @@ class="font-bold text-warning">{{ data_get($application, 'source.name', 'No sour
             </div>
         </div>
 
-        @if ($privateKeyId)
+        @if (!is_null($privateKeyId))
             <h3 class="pt-4">Deploy Key</h3>
             <div class="py-2 pt-4">Currently attached Private Key: <span
                     class="dark:text-warning">{{ $privateKeyName }}</span>

tests/Feature/ApplicationSourceLocalhostKeyTest.php

@@ -0,0 +1,59 @@
+<?php
+
+use App\Livewire\Project\Application\Source;
+use App\Models\Application;
+use App\Models\Environment;
+use App\Models\PrivateKey;
+use App\Models\Project;
+use App\Models\Team;
+use App\Models\User;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Livewire\Livewire;
+
+uses(RefreshDatabase::class);
+
+beforeEach(function () {
+    $this->team = Team::factory()->create();
+    $this->user = User::factory()->create();
+    $this->team->members()->attach($this->user->id, ['role' => 'owner']);
+
+    $this->actingAs($this->user);
+    session(['currentTeam' => $this->team]);
+
+    $this->project = Project::factory()->create(['team_id' => $this->team->id]);
+    $this->environment = Environment::factory()->create(['project_id' => $this->project->id]);
+});
+
+describe('Application Source with localhost key (id=0)', function () {
+    test('renders deploy key section when private_key_id is 0', function () {
+        $privateKey = PrivateKey::create([
+            'id' => 0,
+            'name' => 'localhost',
+            'private_key' => 'test-key-content',
+            'team_id' => $this->team->id,
+        ]);
+
+        $application = Application::factory()->create([
+            'environment_id' => $this->environment->id,
+            'private_key_id' => 0,
+        ]);
+
+        Livewire::test(Source::class, ['application' => $application])
+            ->assertSuccessful()
+            ->assertSet('privateKeyId', 0)
+            ->assertSee('Deploy Key');
+    });
+
+    test('shows no source connected section when private_key_id is null', function () {
+        $application = Application::factory()->create([
+            'environment_id' => $this->environment->id,
+            'private_key_id' => null,
+        ]);
+
+        Livewire::test(Source::class, ['application' => $application])
+            ->assertSuccessful()
+            ->assertSet('privateKeyId', null)
+            ->assertDontSee('Deploy Key')
+            ->assertSee('No source connected');
+    });
+});