feat: implement /timezone command to get/set room timezone

- Add cmd_timezone handler for /timezone command
- Validate timezone using IANA format (zoneinfo.ZoneInfo)
- Use existing BountyService.get_timezone and set_timezone methods
- Admin-only permission via service layer
- Update help text and bot command list
- Fixes #53

apps/telegram-bot/bot.py

@@ -14,6 +14,7 @@ from commands import (
     cmd_help,
     cmd_my,
     cmd_start,
+    cmd_timezone,
     cmd_track,
     cmd_untrack,
     cmd_update,
@@ -41,6 +42,7 @@ def build_app() -> Application:
     app.add_handler(CommandHandler("delete", cmd_delete))
     app.add_handler(CommandHandler("track", cmd_track))
     app.add_handler(CommandHandler("untrack", cmd_untrack))
+    app.add_handler(CommandHandler("timezone", cmd_timezone))
 
     app.add_handler(MessageHandler(filters.COMMAND, cmd_help))
 
@@ -56,6 +58,7 @@ async def post_init(app: Application) -> None:
             ("edit", "Edit a bounty"),
             ("track", "Track a bounty"),
             ("untrack", "Stop tracking"),
+            ("timezone", "Get/set room timezone"),
             ("help", "Show help"),
         ]
     )