fix(issue-57): review nits - a damaged audit sequence or an unresolvable log root never aborts the check

_check_disk_fallback converted transition_seq outside its try, so a
status.json whose sequence is not an integer would raise out of the
subscriber's main loop; such a status is now ignored with a warning, like a
stale one. delegate_started_recorded returned 1 before looking at the
registry's events.log when the audit-log root could not be resolved; it now
skips only the audit check.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

tests/test_issue57_logs_follow_registry.py

@@ -369,6 +369,12 @@ def test_old_audit_terminal_does_not_complete_the_redispatched_attempt(moved, mo
     pending, terminal = {jid}, {}
     job_subscriber._check_disk_fallback(pending, str(reg), terminal, {jid: rec["dispatch_token"]}, {jid: 2})
     assert pending == {jid} and terminal == {}
+    # a damaged sequence is ignored too, and does not take the subscriber down
+    mqtt_common.job_log_path(jid, mqtt_common.STATUS_FILENAME, str(logs)).write_text(
+        json.dumps({"job_id": jid, "status": "completed", "transition_seq": "n/a"}))
+    pending, terminal = {jid}, {}
+    job_subscriber._check_disk_fallback(pending, str(reg), terminal, {jid: rec["dispatch_token"]}, {jid: 2})
+    assert pending == {jid} and terminal == {}
     # a newer audit-only terminal is still taken
     mqtt_common.update_logged_status(jid, "completed", logs_dir=str(logs), transition_seq=rec["transition_seq"] + 1)
     pending, terminal = {jid}, {}