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/src/Filament/Resources/Customers/CustomerResource.php

@@ -0,0 +1,63 @@
+<?php
+
+namespace Modules\Identity\Filament\Resources\Customers;
+
+use App\Models\User;
+use BackedEnum;
+use Filament\Resources\Resource;
+use Filament\Schemas\Schema;
+use Filament\Support\Icons\Heroicon;
+use Filament\Tables\Table;
+use Illuminate\Database\Eloquent\Builder;
+use Modules\Identity\Filament\Resources\Customers\Pages\ListCustomers;
+use Modules\Identity\Filament\Resources\Customers\Pages\ViewCustomer;
+use Modules\Identity\Filament\Resources\Customers\Schemas\CustomerInfolist;
+use Modules\Identity\Filament\Resources\Customers\Tables\CustomersTable;
+use UnitEnum;
+
+/**
+ * Customers are `users` rows carrying no role at all — the inverse scope of
+ * StaffResource (domain.md §4, single `users` table). Read-only by design:
+ * customer accounts are created via the mini app/mobile token flow (T1.2),
+ * never hand-entered by staff.
+ */
+class CustomerResource extends Resource
+{
+    protected static ?string $model = User::class;
+
+    protected static string|BackedEnum|null $navigationIcon = Heroicon::OutlinedUsers;
+
+    protected static string|UnitEnum|null $navigationGroup = 'Access';
+
+    protected static ?string $navigationLabel = 'Customers';
+
+    protected static ?string $modelLabel = 'Customer';
+
+    public static function getEloquentQuery(): Builder
+    {
+        return parent::getEloquentQuery()->doesntHave('roles');
+    }
+
+    public static function table(Table $table): Table
+    {
+        return CustomersTable::configure($table);
+    }
+
+    public static function infolist(Schema $schema): Schema
+    {
+        return CustomerInfolist::configure($schema);
+    }
+
+    public static function getPages(): array
+    {
+        return [
+            'index' => ListCustomers::route('/'),
+            'view' => ViewCustomer::route('/{record}'),
+        ];
+    }
+
+    public static function canViewAny(): bool
+    {
+        return auth()->user()?->can('view_customers') ?? false;
+    }
+}