feat: add subscription and transaction repositories

- Implemented SubscriptionRepository with methods to get, create, and update subscriptions.
- Added BalanceTXRepository for creating and retrieving balance transactions.
- Introduced a test script for simulating Pally webhook for local testing.

repositories/subscriptions.py

@@ -0,0 +1,74 @@
+from datetime import datetime
+
+from sqlalchemy import select, update
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from db.models.subscriptions import Subscription, SubscriptionStatus
+
+
+class SubscriptionRepository:
+    async def get_subscription_by_user_id(
+        self, session: AsyncSession, user_id: int
+    ) -> Subscription | None:
+        stmt = select(Subscription).where(Subscription.user_id == user_id)
+        res = await session.execute(stmt)
+        return res.scalar_one_or_none()
+
+    async def create_subscription(
+        self,
+        session: AsyncSession,
+        *,
+        user_id: int,
+        end_date: datetime,
+        devices: int,
+        duration_days: int,
+        plan_price_paid: int,
+        whitelists: bool,
+        autorenew: bool = False,
+        status: SubscriptionStatus = SubscriptionStatus.EXPIRED,
+    ) -> Subscription:
+        subscription = Subscription(
+            user_id=user_id,
+            end_date=end_date,
+            autorenew=autorenew,
+            status=status,
+            devices=devices,
+            whitelists=whitelists,
+            duration_days=duration_days,
+            plan_price_paid=plan_price_paid,
+        )
+        session.add(subscription)
+        await session.commit()
+
+        return subscription
+
+    async def update_sub(
+        self,
+        session: AsyncSession,
+        user_id: int,
+        *,
+        end_date: datetime,
+        devices: int,
+        whitelists: bool,
+        duration_days: int,
+        plan_price_paid: int,
+        autorenew: bool = False,
+        status: SubscriptionStatus = SubscriptionStatus.ACTIVE,
+    ) -> Subscription | None:
+        stmt = (
+            update(Subscription)
+            .where(Subscription.user_id == user_id)
+            .values(
+                end_date=end_date,
+                autorenew=autorenew,
+                status=status,
+                devices=devices,
+                whitelists=whitelists,
+                duration_days=duration_days,
+                plan_price_paid=plan_price_paid,
+            )
+            .returning(Subscription)
+        )
+        result = await session.execute(stmt)
+        await session.commit()
+        return result.scalar_one_or_none()