feat: add SQLAlchemy async engine and session factory

src/proxy_pool/db/base.py

@@ -0,0 +1,22 @@
+import uuid
+from datetime import datetime
+
+from sqlalchemy import func
+from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column
+
+
+class Base(DeclarativeBase):
+    pass
+
+
+class UUIDPrimaryKeyMixin:
+    id: Mapped[uuid.UUID] = mapped_column(
+        primary_key=True,
+        default_factory=uuid.uuid4,
+    )
+
+
+class TimestampMixin:
+    created_at: Mapped[datetime] = mapped_column(
+        server_default=func.now(),
+    )

src/proxy_pool/db/session.py

@@ -0,0 +1,21 @@
+from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
+
+from proxy_pool.config import Settings
+
+
+def create_engine(settings: Settings):
+    return create_async_engine(
+        settings.database_url,
+        pool_size=settings.db_pool_size,
+        max_overflow=settings.db_max_overflow,
+        echo=settings.log_level == "DEBUG",
+    )
+
+
+def create_session_factory(settings: Settings) -> async_sessionmaker[AsyncSession]:
+    engine = create_engine(settings)
+    return async_sessionmaker(
+        engine,
+        class_=AsyncSession,
+        expire_on_commit=False,
+    )