Widgets tab links the external demo when config.json names one (demo_url)

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

internal/api/server.go

@@ -736,10 +736,12 @@ func (s *Server) me(w http.ResponseWriter, _ *http.Request) {
 		}
 	}
 	_, rebootErr := os.Stat("/run/reboot-required")
+	var demoURL string
+	s.cfg.View(func(c *config.Config) { demoURL = c.DemoURL })
 	jsonOK(w, 200, map[string]any{
 		"host": s.host, "user": s.user, "version": s.version,
 		"load": load, "uptime": uptime, "service_started": s.started,
-		"reboot_needed": rebootErr == nil, "fingerprint": s.fingerprint, "arch": runtime.GOARCH,
+		"reboot_needed": rebootErr == nil, "fingerprint": s.fingerprint, "arch": runtime.GOARCH, "demo_url": demoURL,
 	})
 }
 

internal/config/config.go

@@ -44,6 +44,9 @@ type Config struct {
 	TLS          string  `json:"tls,omitempty"` // "auto" → self-signed cert in the data dir; "" → plain HTTP
 	Tokens       []Token `json:"tokens,omitempty"`
 	Nodes        []Node  `json:"nodes,omitempty"`
+	// DemoURL, when set, is linked from the Widgets tab: a page outside Ham Lab that
+	// shows the sensor API being used (examples/external-demo).
+	DemoURL string `json:"demo_url,omitempty"`
 
 	path string
 	mu   sync.Mutex