feat: add /voice command for auto voice reply in Telegram gateway

- /voice on: reply with voice when user sends voice messages
- /voice tts: reply with voice to all messages
- /voice off: disable, text-only replies
- /voice status: show current mode
- Per-chat state persisted to gateway_voice_mode.json
- Dedup: skips auto-reply if agent already called text_to_speech tool
- drop_pending_updates=True to ignore stale Telegram messages on restart
- 25 tests covering command handler, reply logic, and edge cases

gateway/platforms/telegram.py

@@ -150,7 +150,10 @@ class TelegramAdapter(BasePlatformAdapter):
             # Start polling in background
             await self._app.initialize()
             await self._app.start()
-            await self._app.updater.start_polling(allowed_updates=Update.ALL_TYPES)
+            await self._app.updater.start_polling(
+                allowed_updates=Update.ALL_TYPES,
+                drop_pending_updates=True,
+            )
             
             # Register bot commands so Telegram shows a hint menu when users type /
             try:
@@ -174,6 +177,7 @@ class TelegramAdapter(BasePlatformAdapter):
                     BotCommand("insights", "Show usage insights and analytics"),
                     BotCommand("update", "Update Hermes to the latest version"),
                     BotCommand("reload_mcp", "Reload MCP servers from config"),
+                    BotCommand("voice", "Toggle voice reply mode"),
                     BotCommand("help", "Show available commands"),
                 ])
             except Exception as e: