Core setting admin UI

[Mikearaya]

Summary

• Adds @unchainedshop/core-settings module — a runtime key-value settings store backed by MongoDB with namespace-scoped Zod schema validation, default values, and public/private visibility
• Exposes GraphQL queries (shopSettingsSchema, shopSettingsNamespaces, shopInfo.settings) and mutation (updateShopSettings) behind manageShopSettings permission, plus an MCP resource for AI integrations
• Implements admin UI settings section with a dynamic form renderer (SchemaField) that maps JSON Schema types (string, number, boolean, enum, nested objects) to existing form field components
• Includes a sample shop settings namespace in the kitchensink example demonstrating real-world configuration (site name, support email, guest checkout, maintenance mode, notification preferences)

How it works

1. Namespaces are registered at boot via registerSettingsNamespace({ key, schema, public, defaults }) before startPlatform()
2. Zod schemas are converted to JSON Schema and served via shopSettingsSchema(namespace) for the admin UI to generate forms dynamically
3. Public namespaces are readable without authentication via shopInfo.settings(namespace) for storefront use
4. The admin UI lists registered namespaces at /settings and renders an inline detail page with schema-driven form fields when a namespace is selected

Test plan

• Start kitchensink example and verify the shop namespace appears in admin UI under Settings
• Click the shop namespace and verify the form renders all fields (text, number, checkbox, nested object)
• Submit the form and verify values persist across page reloads
• Verify public namespace settings are accessible without auth via shopInfo { settings(namespace: "shop") }
• Verify a user without manageShopSettings sees a read-only form