feat(trash): SoftDeleteMixin applied to the 7 soft-deletable models

src/fabledassistant/models/base.py

@@ -1,9 +1,18 @@
 from datetime import datetime, timezone
 
-from sqlalchemy import DateTime
+from sqlalchemy import DateTime, Text
 from sqlalchemy.orm import Mapped, mapped_column
 
 
+class SoftDeleteMixin:
+    """Recoverable-delete columns. NULL deleted_at = live row. deleted_batch_id
+    groups rows soft-deleted in one operation so a cascade restores as a unit."""
+    deleted_at: Mapped[datetime | None] = mapped_column(
+        DateTime(timezone=True), nullable=True, default=None
+    )
+    deleted_batch_id: Mapped[str | None] = mapped_column(Text, nullable=True, default=None)
+
+
 class TimestampMixin:
     created_at: Mapped[datetime] = mapped_column(
         DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)