fix(scheduler,i18n): a failure a job names reads in the reader's language

The audit log showed a failed RSS poll as the server's English sentence
under a Hungarian UI. A job can now raise progress.JobFailed(reason,
message, **params): the scheduler stores the reason and params as the
run's data (dashboard, manual-run notice, audit row) beside the English
line, and the client renders scheduler.failure.<reason>. The RSS outage
names its first channel and the reason code (HTTP 404 vs unreachable).
An upstream's own error text stays as raised (diagnostic).

backend/tests/test_scheduler.py

@@ -86,3 +86,31 @@ def test_a_job_runs_audit_row_carries_its_result_as_data(db):
         {"status": "skipped", "summary": "sync paused", "result": {"skipped": "sync paused"}},
         {"status": "error", "summary": "boom"},
     ]
+
+
+def test_a_failure_the_job_names_rides_along_as_data(db, make_user):
+    """E31: a failed RSS poll reached the Hungarian audit log as the server's English sentence. A
+    failure the job names (`progress.JobFailed`) is stored as data beside that sentence — on the
+    dashboard, the manual-run notice and the audit row — so the client says it in the reader's
+    language. Any other failure keeps only its own text (the test above)."""
+    from app import progress
+    from app.models import AuditLog
+
+    def outage(_db):
+        raise progress.JobFailed("rss_all_failed", "RSS poll failed", total=2, cause="transport")
+
+    admin = make_user("failure@example.com", role="admin")
+    token = scheduler._manual_actor.set(admin.id)
+    try:
+        scheduler._job("rss_poll", outage)
+    finally:
+        scheduler._manual_actor.reset(token)
+
+    named = {"failure": "rss_all_failed", "total": 2, "cause": "transport"}
+    rss = _snapshot_job("rss_poll")
+    assert rss["last_error"] == "RSS poll failed"
+    assert rss["result"] == named
+    notice = db.execute(select(Notification).where(Notification.user_id == admin.id)).scalar_one()
+    assert notice.data["result"] == named
+    row = db.execute(select(AuditLog).order_by(AuditLog.id.desc())).scalars().first()
+    assert row is not None and row.after["result"] == named