fix: use Telegram API to lookup users by username

_find_user_id_by_username now uses ctx.bot.get_chat() to lookup
any user by username, not just bounty creators. This allows
/admin add to work for any user in the group.

apps/telegram-bot/commands.py

@@ -771,15 +771,14 @@ async def cmd_recover(update: Update, ctx: ContextTypes.DEFAULT_TYPE) -> None:
     await update.message.reply_text("\n".join(response_lines))
 
 
-def _find_user_id_by_username(room_id: int, username: str) -> int | None:
-    """Find user_id by username from bounty creators in the room."""
-    bounties = BOUNTY_SERVICE.list_bounties(room_id)
-    for bounty in bounties:
-        if (
-            bounty.created_by_username
-            and bounty.created_by_username.lower() == username.lower()
-        ):
-            return bounty.created_by_user_id
+async def _find_user_id_by_username(
+    ctx: ContextTypes.DEFAULT_TYPE, username: str
+) -> int | None:
+    """Find user_id by username using Telegram API."""
+    try:
+        chat = await ctx.bot.get_chat(f"@{username}")
+        return chat.id
+    except Exception:
         return None
 
 
@@ -845,7 +844,7 @@ async def cmd_admin(update: Update, ctx: ContextTypes.DEFAULT_TYPE) -> None:
         await update.message.reply_text("⛔ Only admins can perform this action.")
         return
 
-    target_user_id = _find_user_id_by_username(room_id, username)
+    target_user_id = await _find_user_id_by_username(ctx, username)
 
     if target_user_id is None:
         await update.message.reply_text(f"⛔ User @{username} not found.")