refactor: factorize duplicated code across handlers and services

.gitignore

@@ -1,2 +1,4 @@
 __pycache__/
 *.pyc
+bot_activity.log
+.coverage

src/handlers/common.py

@@ -1,7 +1,8 @@
+import os
 import logging
 import functools
 from telegram import Update
-from telegram.ext import CallbackContext
+from telegram.ext import CallbackContext, ConversationHandler
 from config import TIMEOUT_NAME, TIMEOUT_FIRE_NAME
 
 
@@ -22,6 +23,39 @@ async def wrapper(update: Update, context: CallbackContext, *args, **kwargs):
     return wrapper
 
 
+def cb_auth_required(func):
+    """Decorator to restrict callback query handler access to allowed users only.
+    Reads the whitelist from context.bot_data['allowed_user_ids'].
+    Returns ConversationHandler.END when access is denied so the conversation
+    is cleanly terminated regardless of the current state.
+    """
+    @functools.wraps(func)
+    async def wrapper(update: Update, context: CallbackContext, *args, **kwargs):
+        query = update.callback_query
+        user_id = str(query.from_user.id)
+        allowed_user_ids = context.bot_data.get('allowed_user_ids', set())
+        if user_id not in allowed_user_ids:
+            await query.answer("Access denied.", show_alert=True)
+            return ConversationHandler.END
+        return await func(update, context, *args, **kwargs)
+    return wrapper
+
+
+def safe_delete_file(path: str) -> None:
+    """Delete a temporary file safely, logging errors without raising.
+
+    :param path: Absolute or relative path to the file to delete.
+    """
+    if not path:
+        return
+    try:
+        if os.path.exists(path):
+            os.remove(path)
+            logging.info("%s has been deleted.", path)
+    except Exception as e:
+        logging.error("Error deleting image file %s: %s", path, e)
+
+
 async def handle_api_error(update: Update, error_data: dict) -> bool:
     """Handle API error responses uniformly.
     Sends an appropriate error photo depending on error type.