Add Access group admin surfaces, booking soft deletes, refund crash fix

Access group (Filament):
- StaffResource: manage users with an admin-tier role, gated by manage_staff
- CustomerResource: read-only view of role-less users, gated by view_customers
- RoleResource: edit permissions per role (fixed role set), gated by manage_roles
- ManageAppSettings: tabbed General/Booking settings page that reads/writes
  real .env keys via new EnvFileWriter (no parallel DB settings table, so
  BookingService/config('booking.*') stay unchanged)
- Moved Access above Catalog in the nav group order
- New permissions: manage_staff, manage_roles, view_customers, manage_settings

Booking soft deletes:
- bookings.deleted_at + SoftDeletes on the Booking model
- BookingPolicy::delete (manage_bookings, cancelled/expired only) and
  ::restore (manage_bookings)
- DeleteBookingTableAction/RestoreBookingTableAction + TrashedFilter on
  BookingsTable, using authorize() so the policy is enforced at call time,
  not just cosmetically hidden

Refund crash fix:
- ProcessRefundAction passed a nullable $payment->booking into
  RefundBookingAction's non-nullable Booking param — a soft-deleted
  booking's payment reaching the refund picker was an uncaught TypeError.
  Excluded such payments from the picker and added a defensive guard.
- Same unguarded $event->payment->booking / $event->refund->payment->booking
  pattern fixed in the MarkBookingPaid/MarkBookingRefunded queued listeners.

289 tests passing.

app-modules/identity/database/seeders/RolePermissionSeeder.php

@@ -21,6 +21,10 @@ class RolePermissionSeeder extends Seeder
         'view_payments',
         'process_refunds',
         'view_audit_log',
+        'manage_staff',
+        'manage_roles',
+        'view_customers',
+        'manage_settings',
     ];
 
     /**
@@ -36,6 +40,10 @@ class RolePermissionSeeder extends Seeder
             'view_payments',
             'process_refunds',
             'view_audit_log',
+            'manage_staff',
+            'manage_roles',
+            'view_customers',
+            'manage_settings',
         ],
         'admin' => [
             'manage_catalog',
@@ -46,11 +54,14 @@ class RolePermissionSeeder extends Seeder
             'view_payments',
             'process_refunds',
             'view_audit_log',
+            'view_customers',
+            'manage_settings',
         ],
         'support' => [
             'view_bookings',
             'view_payments',
             'view_audit_log',
+            'view_customers',
         ],
     ];