Router macros for Dstar pages and components.

# In your Phoenix router:
import Dstar.Router

scope "/", MyAppWeb do
  pipe_through :browser

  dstar "/counter", CounterPage
  dstar_components "/ds", [DetailDrawer, DatePicker]
end

dstar/2 expands to plain Phoenix routes — the route is the code allowlist, not an authorization check:

GET   /counter                 -> Dstar.Page.Plug page    (mount + render)
POST  /counter                 -> Dstar.Page.Plug stream  (authorize + handle_connect + loop)
POST  /counter/_event/:event   -> Dstar.Page.Plug event   (authorize + handle_event)

All three go through the surrounding pipe_through. Use the pipeline for session-wide authentication. mount/2 authorizes only the GET; page-local authorize/2 is the pre-SSE seam for event and stream POSTs. See Dstar.Page.

_event is a reserved path segment under page paths.

dstar_components/2 expands to one POST route on Dstar.Plugs.Dispatch with the given module allowlist. That allowlist selects handler modules; the handler must still authorize the current user before Dstar.start/1 if it needs a normal 401/403.