fix: scanner wire:ignore + Company custom columns

- Scanner page: wrap the html5-qrcode camera container (#reader) in
  wire:ignore so a Livewire DOM morph can't tear down the live camera
  stream (same class of bug as the calendar).
- Company::getCustomColumns(): add `is_demo` and `default_warehouse_id`.
  Stancl Tenant treats columns absent from this list as virtual `data` JSON
  attributes, so editing a company could move default_warehouse_id into data
  and null the real column — breaking WarehouseService::defaultWarehouse.

Full suite: 100 passed.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

app/Models/Central/Company.php

@@ -39,7 +39,7 @@ class Company extends BaseTenant implements HasMedia
         return [
             'id',
             'slug', 'name', 'display_name', 'city', 'phone', 'email', 'contact_name',
-            'status', 'plan_id',
+            'status', 'plan_id', 'is_demo', 'default_warehouse_id',
             'trial_ends_at', 'active_until',
             'settings',
             'created_at', 'updated_at', 'deleted_at',