FluentCart REST and headless clients

Inventory the routes registered by the installed version before designing a client. FluentCart 1.6.0 registers its main REST API under /fluent-cart/v2, but not every browser checkout operation is a REST resource.

Read route-auth-map.md before exposing data or building a headless/mobile client.

Do not derive routes from generic examples

The official developer pages currently contain examples that alternate v1 and v2 and describe generic cart endpoints not registered by the tested 1.6.0 runtime. The main API is v2, while an isolated v1 editor-autosave route also exists; never rewrite a route's version globally. Use rest_get_server()->get_routes(), the installed route files, and controller code as the contract for a pinned version.