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.

app/services/credit.py

@@ -403,6 +403,44 @@ class CreditService:
         finally:
             await session.close()
 
+    async def recharge_user_credits_auto(
+        self,
+        user_id: int,
+    ) -> CreditTransaction | None:
+        """Recharge credits for a user automatically based on their plan.
+
+        Args:
+            user_id: The user ID
+
+        Returns:
+            The created credit transaction if credits were added, None if no recharge
+            needed
+
+        Raises:
+            ValueError: If user not found or has no plan
+
+        """
+        session = self.db_session_factory()
+        try:
+            user_repo = UserRepository(session)
+            user = await user_repo.get_by_id_with_plan(user_id)
+            if not user:
+                msg = f"User {user_id} not found"
+                raise ValueError(msg)
+
+            if not user.plan:
+                msg = f"User {user_id} has no plan assigned"
+                raise ValueError(msg)
+
+            # Call the main method with plan details
+            return await self.recharge_user_credits(
+                user_id,
+                user.plan.credits,
+                user.plan.max_credits,
+            )
+        finally:
+            await session.close()
+
     async def recharge_user_credits(
         self,
         user_id: int,
@@ -556,7 +594,13 @@ class CreditService:
 
                     if transaction:
                         stats["recharged_users"] += 1
-                        stats["total_credits_added"] += transaction.amount
+                        # Calculate the amount from plan data to avoid session issues
+                        current_credits = user.credits
+                        plan_credits = user.plan.credits
+                        max_credits = user.plan.max_credits
+                        target_credits = min(current_credits + plan_credits, max_credits)
+                        credits_added = target_credits - current_credits
+                        stats["total_credits_added"] += credits_added
                     else:
                         stats["skipped_users"] += 1