refactor: define explicit fillable attributes on all Eloquent models

Replace $guarded usage with explicit $fillable arrays across all models.
Sync fillable definitions with current database schema and add tests.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/Models/ApplicationDeploymentQueue.php

@@ -39,7 +39,32 @@ use OpenApi\Attributes as OA;
 )]
 class ApplicationDeploymentQueue extends Model
 {
-    protected $guarded = [];
+    protected $fillable = [
+        'application_id',
+        'deployment_uuid',
+        'pull_request_id',
+        'force_rebuild',
+        'commit',
+        'status',
+        'is_webhook',
+        'logs',
+        'current_process_id',
+        'restart_only',
+        'git_type',
+        'server_id',
+        'application_name',
+        'server_name',
+        'deployment_url',
+        'destination_id',
+        'only_this_server',
+        'rollback',
+        'commit_message',
+        'is_api',
+        'build_server_id',
+        'horizon_job_id',
+        'horizon_job_worker',
+        'finished_at',
+    ];
 
     protected $casts = [
         'finished_at' => 'datetime',