Phase 6: security & ops hardening (T6.1-T6.5)

- T6.1: named rate limiters (api-read/api-write/api-auth/api-webhooks),
  applied per module route group with tighter limits on booking/payment
  writes and the KBZ webhook than read-only catalog/routing endpoints.
- T6.2: install spatie/laravel-activitylog; LogsActivity on Booking/
  Payment/Refund status transitions and catalog/pricing admin CRUD
  (EvCompany, Destination, DepartureTimeSlot, EvRoute, RoutePricing).
  New IdentityPlugin with a read-only AuditLogResource gated by
  view_audit_log.
- T6.3: JSON error envelope for api/* in bootstrap/app.php (401/403/404/
  405/429/500 fallback), plus PaymentGatewayException (422 declined /
  502 unavailable).
- T6.4: feature tests proving the FastAPI agent token gets 403 on
  refund/cancel-not-owned and 405 (no write handler) on catalog/routing
  writes.
- T6.5: install gboquizosanchez/filament-log-viewer with a custom
  Filament admin theme (required for its views' Tailwind classes to
  compile), LOG_CHANNEL/FILAMENT_LOG_VIEWER_DRIVER=daily, registered
  under Operations in the sidebar.

252 tests passing.

app-modules/identity/src/Policies/AuditLogPolicy.php

@@ -0,0 +1,39 @@
+<?php
+
+namespace Modules\Identity\Policies;
+
+use App\Models\User;
+use Spatie\Activitylog\Models\Activity;
+
+/**
+ * The audit trail (T6.2) is read-only from the admin panel — nothing ever
+ * creates/edits/deletes an Activity row through Filament, only the
+ * LogsActivity trait writes here. Gated by view_audit_log per domain.md §8.
+ */
+class AuditLogPolicy
+{
+    public function viewAny(User $user): bool
+    {
+        return $user->can('view_audit_log');
+    }
+
+    public function view(User $user, Activity $activity): bool
+    {
+        return $user->can('view_audit_log');
+    }
+
+    public function create(User $user): bool
+    {
+        return false;
+    }
+
+    public function update(User $user, Activity $activity): bool
+    {
+        return false;
+    }
+
+    public function delete(User $user, Activity $activity): bool
+    {
+        return false;
+    }
+}