fix(discord): don't auto-disconnect voice when reply mode is off

The voice inactivity timer (VOICE_TIMEOUT) only counted the bot's OWN audio
playback as activity. Under /voice off (text-only replies, but still in the
channel — leaving is /voice leave) nothing ever reset it, so every 300s the bot
disconnected and spammed "Left voice channel (inactivity timeout)."

The adapter now learns the live voice-reply mode via a getter wired from run.py
and skips the auto-disconnect while mode is off. It also resets the timer when a
user actually speaks to the bot, so an active listener (incl. voice-on
text-only sessions that never play audio) isn't dropped mid-conversation.

gateway/run.py

@@ -9367,6 +9367,12 @@ class GatewayRunner(GatewayAuthorizationMixin, GatewayKanbanWatchersMixin, Gatew
             adapter._voice_input_callback = self._handle_voice_channel_input
         if hasattr(adapter, "_on_voice_disconnect"):
             adapter._on_voice_disconnect = self._handle_voice_timeout_cleanup
+        # Let the adapter's inactivity timer see the live voice-reply mode so it
+        # doesn't disconnect a deliberately text-only (/voice off) session.
+        if hasattr(adapter, "_voice_mode_getter"):
+            adapter._voice_mode_getter = lambda chat_id: self._voice_mode.get(
+                self._voice_key(Platform.DISCORD, str(chat_id)), "off"
+            )
 
         try:
             success = await adapter.join_voice_channel(voice_channel)