Join one FM-Funknetz talk group from a headset window.

The station reads ~/.funknetz.json, speaks protocol 2.0, and builds an unsigned funknetz.app.

Co-authored-by: Cursor <cursoragent@cursor.com>

station/clock.go

@@ -0,0 +1,32 @@
+package station
+
+import "time"
+
+// Clock is the time source for heartbeats and the retry wait.
+type Clock interface {
+	Now() time.Time
+	NewTimer(d time.Duration) Timer
+}
+
+// Timer is a single deadline. Stop prevents the channel from firing.
+type Timer interface {
+	C() <-chan time.Time
+	Stop() bool
+}
+
+type wallClock struct{}
+
+func (wallClock) Now() time.Time { return time.Now() }
+
+func (wallClock) NewTimer(d time.Duration) Timer {
+	if d < 0 {
+		d = 0
+	}
+	return wallTimer{t: time.NewTimer(d)}
+}
+
+type wallTimer struct{ t *time.Timer }
+
+func (w wallTimer) C() <-chan time.Time { return w.t.C }
+
+func (w wallTimer) Stop() bool { return w.t.Stop() }