Implement duty schedule import functionality and enhance user management

- Added a new command `/import_duty_schedule` for importing duty schedules via JSON, restricted to admin users.
- Introduced a two-step import process: specifying handover time and uploading a JSON file.
- Updated the database schema to allow `telegram_user_id` to be nullable for user creation by full name.
- Implemented repository functions for user management, including `get_or_create_user_by_full_name` and `delete_duties_in_range`.
- Enhanced README documentation with details on the new import command and JSON format requirements.
- Added comprehensive tests for the duty schedule parser and integration tests for the import functionality.

handlers/commands.py

@@ -46,10 +46,16 @@ async def start(update: Update, context: ContextTypes.DEFAULT_TYPE) -> None:
 
 
 async def help_cmd(update: Update, context: ContextTypes.DEFAULT_TYPE) -> None:
-    if update.message:
-        await update.message.reply_text(
-            "Доступные команды:\n/start — Начать\n/help — Показать эту справку"
-        )
+    if not update.message or not update.effective_user:
+        return
+    lines = [
+        "Доступные команды:",
+        "/start — Начать",
+        "/help — Показать эту справку",
+    ]
+    if config.is_admin(update.effective_user.username or ""):
+        lines.append("/import_duty_schedule — Импорт расписания дежурств (JSON)")
+    await update.message.reply_text("\n".join(lines))
 
 
 start_handler = CommandHandler("start", start)