feat: add /admin command to list room admins

Implement /admin command as specified in issue #50:
- Lists all admin user IDs for the current room
- Output format: 'Room Admins:\n- @user1\n- @user2'
- Shows 'No admins configured for this room.' if none exist
- Available to everyone (no permission check needed)

Changes:
- Add cmd_admin function to commands.py
- Register CommandHandler('admin', cmd_admin) in bot.py
- Add /admin to command menu in post_init
- Update /help to include /admin command

Closes #50

apps/telegram-bot/bot.py

@@ -8,6 +8,7 @@ from telegram.ext import Application, CommandHandler, MessageHandler, filters
 
 from commands import (
     cmd_add,
+    cmd_admin,
     cmd_bounty,
     cmd_delete,
     cmd_edit,
@@ -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("admin", cmd_admin))
 
     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"),
+            ("admin", "List room admins"),
             ("help", "Show help"),
         ]
     )