fix(migrations): dropping the demo also takes its reset job's interval-change audit rows

0098 deleted the reset job's run rows but not the scheduler_interval rows that changing its interval
wrote; with the job's label gone they rendered as a raw id. The delete now takes every job-targeted
row for it, and a test seeds both kinds below 0098 and upgrades (red on the old filter). The test
has its own file so the removed-features guard can name it.

backend/tests/test_migration_0098.py

@@ -0,0 +1,35 @@
+"""Migration 0098's data cleanup, DB-lane.
+
+The schema half of every migration is checked by test_migrations.py; this one also deletes rows, and
+a delete that misses a row is invisible there. Its own file so the removed-features guard can name it.
+"""
+
+from alembic import command
+from alembic.config import Config
+from sqlalchemy import text
+
+from app.db import engine
+
+
+def test_dropping_the_demo_takes_every_audit_row_about_its_reset_job(db):
+    # The reset job's interval could be changed from the scheduler page like any job's; once its
+    # name is gone from the UI, a left-behind row would render as a raw job id.
+    cfg = Config("alembic.ini")
+    command.downgrade(cfg, "0097_drop_messages")
+    try:
+        with engine.begin() as conn:
+            conn.execute(
+                text(
+                    "INSERT INTO audit_log (action, target_type, target_id, created_at) VALUES"
+                    " ('job_run', 'job', 'demo_reset', now()),"
+                    " ('scheduler_interval', 'job', 'demo_reset', now()),"
+                    " ('scheduler_interval', 'job', 'sync_feed', now())"
+                )
+            )
+    finally:
+        command.upgrade(cfg, "head")
+    with engine.connect() as conn:
+        left = conn.execute(
+            text("SELECT action, target_id FROM audit_log WHERE target_type = 'job' ORDER BY id")
+        ).all()
+    assert [tuple(r) for r in left] == [("scheduler_interval", "sync_feed")]