Add global search API and command palette (Cmd+K)

[Mikearaya]

• Add Query.globalSearch GraphQL endpoint that searches across products, users, orders, assortments, filters, enrollments, quotations, and work items in a single request
• Per-type ACL enforcement: each entity type maps to its own permission action (e.g. viewUsers, viewOrders, manageAssortments). Before searching, all requested types are checked via checkAction — if the user lacks permission for any requested type, the query throws (not silent filtering). Callers can limit the types argument to only search entities they have access to.
• Add command palette UI (⌘K / Ctrl+K) to admin-ui with keyboard navigation, type-aware result rendering (images, icons, labels), debounced search, i18n, and "view all" links per entity type

How to test

• Open admin-ui, press ⌘K (or Ctrl+K) — palette opens
• Type a search term — results appear grouped with correct icons/images
• Arrow keys navigate results, Enter opens the selected item
• Click a result — navigates to correct detail page
• Verify ACL: user without order access gets a permission error when ORDERS is in types
• Verify ACL: omitting types param searches all types the user has access to — throws if any type is unauthorized
• ESC or clicking backdrop closes the palette
• Mobile: search button visible in top bar