feat(deployments): track application configuration diffs

Store deployment configuration snapshots on application deployment queues and compare them against the current application state. Surface grouped pending changes in the configuration checker and use build-impact diffs to decide when an existing image can skip the build step.

app/Models/ApplicationDeploymentQueue.php

@@ -17,6 +17,9 @@ use OpenApi\Attributes as OA;
         'deployment_uuid' => ['type' => 'string'],
         'pull_request_id' => ['type' => 'integer'],
         'docker_registry_image_tag' => ['type' => 'string', 'nullable' => true],
+        'configuration_hash' => ['type' => 'string', 'nullable' => true],
+        'configuration_snapshot' => ['type' => 'object', 'nullable' => true],
+        'configuration_diff' => ['type' => 'object', 'nullable' => true],
         'force_rebuild' => ['type' => 'boolean'],
         'commit' => ['type' => 'string'],
         'status' => ['type' => 'string'],
@@ -45,6 +48,9 @@ class ApplicationDeploymentQueue extends Model
         'deployment_uuid',
         'pull_request_id',
         'docker_registry_image_tag',
+        'configuration_hash',
+        'configuration_snapshot',
+        'configuration_diff',
         'force_rebuild',
         'commit',
         'status',
@@ -71,6 +77,8 @@ class ApplicationDeploymentQueue extends Model
     protected $casts = [
         'pull_request_id' => 'integer',
         'finished_at' => 'datetime',
+        'configuration_snapshot' => 'array',
+        'configuration_diff' => 'array',
     ];
 
     public function application()