init: new structure + fix lint errors

cpv3/db/base.py

@@ -0,0 +1,25 @@
+from __future__ import annotations
+
+import uuid
+from datetime import datetime, timezone
+
+from sqlalchemy import Boolean, DateTime
+from sqlalchemy.dialects.postgresql import UUID
+from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column
+
+
+def utcnow() -> datetime:
+    return datetime.now(timezone.utc)
+
+
+class Base(DeclarativeBase):
+    pass
+
+
+class BaseModelMixin:
+    id: Mapped[uuid.UUID] = mapped_column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=utcnow)
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), default=utcnow, onupdate=utcnow
+    )
+    is_active: Mapped[bool] = mapped_column(Boolean, default=True)