Implement FastAPI Temporal MVP pipeline

app/infra/db/base.py

@@ -0,0 +1,33 @@
+"""Database base declarations."""
+
+from datetime import datetime, timezone
+
+from sqlalchemy import DateTime
+from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column
+
+
+def utc_now() -> datetime:
+    """Return the current UTC timestamp."""
+
+    return datetime.now(timezone.utc)
+
+
+class Base(DeclarativeBase):
+    """Shared declarative base."""
+
+
+class TimestampMixin:
+    """Mixin that adds created and updated timestamps."""
+
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        default=utc_now,
+        nullable=False,
+    )
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        default=utc_now,
+        onupdate=utc_now,
+        nullable=False,
+    )
+