Add admin dashboard at / with bearer-token overview API

internal/server/api.go

@@ -7,6 +7,7 @@ import (
 	"mime"
 	"net/http"
 	"strings"
+	"time"
 )
 
 // API is the HTTP control plane. Its answers match the recorded contract in
@@ -15,6 +16,10 @@ type API struct {
 	Store  *Store
 	Hub    *Hub
 	Domain string
+
+	AdminToken string    // bearer token for /api/admin/*; empty disables it
+	StartedAt  time.Time // for the uptime shown on the dashboard
+	Version    string
 }
 
 func (a *API) ServeHTTP(w http.ResponseWriter, r *http.Request) {
@@ -27,6 +32,10 @@ func (a *API) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		w.Write([]byte(`{"ok":true}`))
 	case path == "/openapi.json" && r.Method == http.MethodGet:
 		writeJSON(w, http.StatusOK, json.RawMessage(openapiStub))
+	case (path == "/" || path == "/admin") && r.Method == http.MethodGet:
+		a.dashboard(w, r)
+	case path == "/api/admin/overview" && r.Method == http.MethodGet:
+		a.adminOverviewHandler(w, r)
 	case path == "/api/tunnel" && r.Method == http.MethodPost:
 		a.createTunnel(w, r)
 	default: