Add Alembic for database migrations and initial migration scripts

- Created alembic.ini configuration file for Alembic migrations.
- Added README file for Alembic with a brief description.
- Implemented env.py for Alembic to manage database migrations.
- Created script.py.mako template for migration scripts.
- Added initial migration script to create database tables.
- Created a migration script to add initial plan and playlist data.
- Updated database initialization to run Alembic migrations.
- Enhanced credit service to automatically recharge user credits based on their plan.
- Implemented delete_task method in scheduler service to remove scheduled tasks.
- Updated scheduler API to reflect task deletion instead of cancellation.
- Added CLI tool for managing database migrations.
- Updated tests to cover new functionality for task deletion and credit recharge.
- Updated pyproject.toml and lock files to include Alembic as a dependency.

tests/test_task_handlers.py

@@ -92,14 +92,14 @@ class TestTaskHandlerRegistry:
             parameters={"user_id": str(test_user_id)},
         )
 
-        mock_credit_service.recharge_user_credits.return_value = {
-            "user_id": str(test_user_id),
-            "credits_added": 100,
-        }
+        # Mock transaction object
+        mock_transaction = MagicMock()
+        mock_transaction.amount = 100
+        mock_credit_service.recharge_user_credits_auto.return_value = mock_transaction
 
         await task_registry.execute_task(task)
 
-        mock_credit_service.recharge_user_credits.assert_called_once_with(test_user_id)
+        mock_credit_service.recharge_user_credits_auto.assert_called_once_with(test_user_id)
 
     async def test_handle_credit_recharge_uuid_user_id(
         self,
@@ -117,7 +117,7 @@ class TestTaskHandlerRegistry:
 
         await task_registry.execute_task(task)
 
-        mock_credit_service.recharge_user_credits.assert_called_once_with(test_user_id)
+        mock_credit_service.recharge_user_credits_auto.assert_called_once_with(test_user_id)
 
     async def test_handle_play_sound_success(
         self,