fix(watcher): resume the bot backlog from a saved cursor instead of restarting it

backend/migrations/versions/b6d1f4a82e57_bot_backlog_cursor.py

@@ -0,0 +1,34 @@
+"""bot backlog cursor
+
+Revision ID: b6d1f4a82e57
+Revises: a7f3d2b81c04
+Create Date: 2026-09-19 10:00:00.000000
+
+"""
+
+from collections.abc import Sequence
+
+from alembic import op
+
+revision: str = "b6d1f4a82e57"
+down_revision: str | None = "a7f3d2b81c04"
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+
+def upgrade() -> None:
+    op.execute(
+        "ALTER TABLE watched_bots "
+        "ADD COLUMN backfill_pts integer, "
+        "ADD COLUMN backfill_qts integer, "
+        "ADD COLUMN backfill_date integer"
+    )
+
+
+def downgrade() -> None:
+    op.execute(
+        "ALTER TABLE watched_bots "
+        "DROP COLUMN IF EXISTS backfill_pts, "
+        "DROP COLUMN IF EXISTS backfill_qts, "
+        "DROP COLUMN IF EXISTS backfill_date"
+    )