wip: the presets API's shape, answering nothing yet

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

internal/control/adminapi/api.go

@@ -166,6 +166,7 @@ func (a *API) Register(mux Mux) {
 		}
 		writeJSON(w, http.StatusOK, t)
 	})
+	a.registerPresets(mux)
 	mux.HandleFunc("GET /api/v1/models", a.listModels)
 	mux.HandleFunc("GET /api/v1/replicas", a.listReplicas)
 	// Listing is a read and deleting is a separate verb, so a mistyped