test(507): fix the two recovery oracles that could never pass

Both tests were committed without being run. Neither failure was data loss:
- mutating_command_auto_recovers_poisoned_index_before_pending_gate looked
  for titles db-only-a/b/c that its fixture never creates. The fixture's
  three database-only issues carry the WAL-only title, and all three
  survived. The test now requires exactly those three plus the new issue.
- poisoned_current_schema_recovers_without_jsonl_rebuild_and_is_repeatable
  unwrapped list --json as a bare array; the output is an object with an
  issues array.

Both now pass as a non-root user on macOS as well as on a Linux worker.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>