feat: split initial social schema migration chain

replace monolithic migration with ordered scripts, include profiles/sessions in migration, and verify full downgrade/upgrade cycle for clean Supabase bootstrap

backend/src/models/automation_jobs.py

@@ -0,0 +1,72 @@
+from __future__ import annotations
+
+import uuid
+from datetime import datetime
+from enum import Enum
+
+from sqlalchemy import DateTime, String, Text
+from sqlalchemy.dialects.postgresql import UUID
+from sqlalchemy.orm import Mapped, mapped_column
+
+from core.db.base import Base, SoftDeleteMixin, TimestampMixin
+
+
+class AutomationJobStatus(str, Enum):
+    ACTIVE = "active"
+    DISABLED = "disabled"
+
+
+class ScheduleType(str, Enum):
+    DAILY = "daily"
+    WEEKLY = "weekly"
+
+
+class AutomationJob(TimestampMixin, SoftDeleteMixin, Base):
+    __tablename__: str = "automation_jobs"
+    __table_args__ = {"extend_existing": True}
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    owner_id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True),
+        nullable=False,
+    )
+    title: Mapped[str] = mapped_column(
+        String(255),
+        nullable=False,
+    )
+    prompt: Mapped[str] = mapped_column(
+        Text,
+        nullable=False,
+    )
+    schedule_type: Mapped[ScheduleType] = mapped_column(
+        String(20),
+        nullable=False,
+    )
+    run_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        nullable=False,
+    )
+    next_run_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        nullable=False,
+    )
+    timezone: Mapped[str] = mapped_column(
+        String(50),
+        nullable=False,
+        default="UTC",
+    )
+    last_run_at: Mapped[datetime | None] = mapped_column(
+        DateTime(timezone=True),
+        nullable=True,
+    )
+    status: Mapped[AutomationJobStatus] = mapped_column(
+        String(20),
+        nullable=False,
+        default=AutomationJobStatus.ACTIVE,
+    )
+    created_by: Mapped[uuid.UUID | None] = mapped_column(
+        UUID(as_uuid=True),
+        nullable=True,
+    )