feat(deployments): support Docker image tags for preview deployments

Add end-to-end support for `docker_registry_image_tag` in preview and deployment queue flows.

- Extend deploy API to accept `pull_request_id` alias and `docker_tag` for preview deploys
- Persist preview-specific Docker tags on `application_previews` and `application_deployment_queues`
- Pass tag through `queue_application_deployment()` and de-duplicate queued jobs by tag
- Update deployment job logic to resolve and use preview Docker tags for dockerimage build packs
- Update Livewire previews UI/state to manage per-preview tags and manual preview/tag inputs
- Add migration for new tag columns and model fillable/casts updates
- Add feature and unit tests covering API behavior and tag resolution

app/Models/ApplicationDeploymentQueue.php

@@ -16,6 +16,7 @@ use OpenApi\Attributes as OA;
         'application_id' => ['type' => 'string'],
         'deployment_uuid' => ['type' => 'string'],
         'pull_request_id' => ['type' => 'integer'],
+        'docker_registry_image_tag' => ['type' => 'string', 'nullable' => true],
         'force_rebuild' => ['type' => 'boolean'],
         'commit' => ['type' => 'string'],
         'status' => ['type' => 'string'],
@@ -67,6 +68,7 @@ class ApplicationDeploymentQueue extends Model
     ];
 
     protected $casts = [
+        'pull_request_id' => 'integer',
         'finished_at' => 'datetime',
     ];