feat: enhance group duty pin command functionality

- Updated the `pin_duty_cmd` to handle cases where no message ID is found by sending a new duty message, pinning it, saving the pin, and scheduling the next update.
- Improved error handling for message sending and pinning operations, providing appropriate replies based on success or failure.
- Enhanced unit tests to cover the new behavior, ensuring proper functionality and error handling in various scenarios.

duty_teller/handlers/group_duty_pin.py

@@ -246,7 +246,34 @@ async def pin_duty_cmd(update: Update, context: ContextTypes.DEFAULT_TYPE) -> No
     loop = asyncio.get_running_loop()
     message_id = await loop.run_in_executor(None, _sync_get_message_id, chat_id)
     if message_id is None:
-        await update.message.reply_text(t(lang, "pin_duty.no_message"))
+        text = await loop.run_in_executor(
+            None, lambda: _get_duty_message_text_sync(lang)
+        )
+        try:
+            msg = await context.bot.send_message(chat_id=chat_id, text=text)
+        except (BadRequest, Forbidden) as e:
+            logger.warning(
+                "Failed to send duty message for pin_duty chat_id=%s: %s", chat_id, e
+            )
+            await update.message.reply_text(t(lang, "pin_duty.failed"))
+            return
+        pinned = False
+        try:
+            await context.bot.pin_chat_message(
+                chat_id=chat_id,
+                message_id=msg.message_id,
+                disable_notification=True,
+            )
+            pinned = True
+        except (BadRequest, Forbidden) as e:
+            logger.warning("Failed to pin message for pin_duty chat_id=%s: %s", chat_id, e)
+        await loop.run_in_executor(None, _sync_save_pin, chat_id, msg.message_id)
+        next_end = await loop.run_in_executor(None, _get_next_shift_end_sync)
+        await _schedule_next_update(context.application, chat_id, next_end)
+        if pinned:
+            await update.message.reply_text(t(lang, "pin_duty.pinned"))
+        else:
+            await update.message.reply_text(t(lang, "pin_duty.could_not_pin_make_admin"))
         return
     try:
         await context.bot.pin_chat_message(