Split MQTT events into dedicated topics

bridge/README.md

@@ -60,8 +60,10 @@ Then upload firmware.
 ## 4) MQTT topics
 
 - Status/events published by bridge:
-  - `evs/<device_id>/status` (JSON)
-  - includes `type: "vad_segment"` when a speech segment is finalized
+  - `evs/<device_id>/status` (connection/start/stop/disconnect)
+  - `evs/<device_id>/mic_level` (mic telemetry)
+  - `evs/<device_id>/vad_segment` (finalized speech segments)
+  - reserved for next steps: `evs/<device_id>/transcript`, `evs/<device_id>/stt_error`
 - Playback input to device:
   - `evs/<device_id>/play_pcm16le`
   - payload options: