feat(mcp): customer_number on create_customer + Beta tags on webshop surfaces (#1677)

* feat(mcp): accept customer_number on gnubok_create_customer

Parity with gnubok_update_customer: a customer number no longer needs a
create-then-update two-step with two approvals. The staged params carry
the trimmed number, commitCreateCustomer inserts it, and the payload-size
ceiling is bumped 59.7K to 59.75K with a documented entry (the property
has no description; name + maxLength are the whole contract).

Requested by a user on Discord 2026-08-16.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* feat(ui): mark webshop integrations and orders tab as Beta

WooCommerce and Shopify rows on the import page get a quiet Beta chip
next to the title, and the webshop /orders sidebar item sets the
existing betaBadge flag. Chip recipe matches the nav beta badge so
Beta reads identically everywhere.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* fix(mcp): enforce customer_number invariants and show it on the approval card

Consolidated resolution pass for PR #1677:
- skeptic (correctness): maxLength 32 was advertisement-only on the create
  path; now enforced with a runtime guard in gnubok_create_customer execute
  (clean errors for non-string and >32) and a 400 guard in
  commitCreateCustomer, matching the web/v1 routes and commitUpdateCustomer.
- skeptic (correctness): CustomerPreview never rendered the staged
  customer_number, leaving the approver blind to the new field; added a
  conditional Kundnr row.
- CodeRabbit: reset the event bus in create-customer.test.ts beforeEach.
- Tests cover both new guards at the tool and executor layers.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

components/dashboard/DashboardNav.tsx

@@ -214,7 +214,7 @@ const navItems: NavItem[] = [
   // hooked up (active WooCommerce/Shopify connection or existing order rows).
   // Deliberately NOT capability-gated: a company whose entitlement lapsed
   // must still reach its already-imported orders (accounting underlag).
-  { href: '/orders', labelKey: 'sales_orders', icon: ShoppingCart, group: 'arbeta', requiresWebshop: true },
+  { href: '/orders', labelKey: 'sales_orders', icon: ShoppingCart, group: 'arbeta', requiresWebshop: true, betaBadge: true },
   { href: '/supplier-invoices', labelKey: 'supplier_invoices', icon: Wallet, group: 'arbeta' },
   { href: '/salary', labelKey: 'salary', icon: HandCoins, group: 'arbeta', employerOnly: true },
   // Körjournal: hidden by default (most companies have no car); shows when