feat(observability): add structured audit log channel for API and webhook events

Introduce a dedicated `audit` log channel (daily rotation, configurable retention via
LOG_AUDIT_DAYS) and a small `auditLog()` / `auditLogWebhookFailure()` helper used to
record state-changing API operations and webhook events.

Instrumented:

- API mutation endpoints (create / update / delete / start / stop / restart) across
  applications, services, databases (incl. backups, env vars, storage), servers,
  projects + environments, scheduled tasks, private keys, GitHub apps, cloud provider
  tokens, Hetzner server provisioning, instance enable/disable.
- Webhook signature verification outcomes for GitHub, GitLab, Bitbucket, Gitea and
  Stripe, plus the Sentinel push endpoint.
- Authentication and authorization outcomes via the global exception handler and
  the `ApiAbility` middleware (unauthenticated, ability-denied, policy-denied).

The helper is wrapped in try/catch so logging failures never affect the request
path. Successful operations log at `info`; suspicious/denied requests log at
`warning`. Operators wanting a failures-only feed can set `LOG_AUDIT_LEVEL=warning`.

Includes a feature test suite covering the helper, the webhook providers and the
new auth/authorization log paths.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

app/Http/Controllers/Api/DeployController.php

@@ -281,6 +281,14 @@ class DeployController extends Controller
                 }
             }
 
+            auditLog('api.deployment.cancelled', [
+                'team_id' => $teamId,
+                'deployment_uuid' => $deployment->deployment_uuid,
+                'application_id' => $application?->id,
+                'application_uuid' => $application?->uuid,
+                'server_id' => $deployment->server_id,
+            ]);
+
             return response()->json([
                 'message' => 'Deployment cancelled successfully.',
                 'deployment_uuid' => $deployment->deployment_uuid,
@@ -518,6 +526,14 @@ class DeployController extends Controller
                     $message = $result['message'];
                 } else {
                     $message = "Application {$resource->name} deployment queued.";
+                    auditLog('api.deployment.triggered', [
+                        'resource_type' => 'application',
+                        'application_uuid' => $resource->uuid,
+                        'application_name' => $resource->name,
+                        'deployment_uuid' => $deployment_uuid?->toString(),
+                        'force_rebuild' => $force,
+                        'pull_request_id' => $pr,
+                    ]);
                 }
                 break;
             case Service::class:
@@ -529,6 +545,10 @@ class DeployController extends Controller
                 }
                 StartService::run($resource);
                 $message = "Service {$resource->name} started. It could take a while, be patient.";
+                auditLog('api.service.deployed', [
+                    'service_uuid' => $resource->uuid,
+                    'service_name' => $resource->name,
+                ]);
                 break;
             default:
                 // Database resource - check authorization
@@ -543,6 +563,11 @@ class DeployController extends Controller
                 $resource->save();
 
                 $message = "Database {$resource->name} started.";
+                auditLog('api.database.started', [
+                    'database_uuid' => $resource->uuid,
+                    'database_name' => $resource->name,
+                    'database_type' => $resource->getMorphClass(),
+                ]);
                 break;
         }