FreeTLab
7eaa87b462
The ringing screen only confirmed the native-to-Flutter handoff from its playback-state listener, but app.dart pre-starts the station before pushing the screen, so `reproduciendo` could be emitted before the listener subscribed and no further event ever arrived. That branch only cancelled the fallback timer: the gated fade-in never started and the native alarm player was never told to stop, so the alarm blared at the alarm-stream volume with no 5%-to-target ramp. Previously this was a timing race the stream usually lost; gating the ramp on the confirmation made the failure deterministic. The already-playing branch now confirms the handoff explicitly (idempotent with the listener), and the ramp re-imposes its 5% start volume immediately instead of waiting for the first periodic tick. Adds the regression test mounting in the real pre-started path.