#4090 test(daemon): retain sanitized evidence on idle cleanup failure

Summary

Preserve evidence when the daemon idle-reap test fails before its temporary state is removed. Append the existing identity reader's PID/start time, info/lock presence and selected removal/finish phase/reason/code to the original assertion error. Tokens, raw registration/log data and error messages are excluded. Unreadable diagnostics leave the original failure intact.

One test file changed; no new tests, runtime/API changes, budget changes or ownership-fence changes. Refs #4086; part of #4045. This adds observability, not a fix or reproduction claim for the intermittent failures.

Validation

Head: eae13bce45b94dabce7cc2fc200ca8514df9792a.

• Frozen install/build, full format and all seven focused entrypoint tests passed.
• Disposable fault proof: baseline/restored idle case each passed; forced unproven identity and thrown finish each failed the original assertion with the expected evidence. Token/private-note/error-message sentinels stayed absent. Identical command/default workers; checkout removed and source state preserved.
• Independent source review: no findings, no tests run by reviewer.
• Full exact-head validation passed tooling, Fallow and unit: 1,849 files / 16,447 passed / one skipped (run-804amS, exactCommit: true). The two original full-suite failures remain unexplained; base unit passed and the phase probe passed eight cases. SDK registration API work is deferred separately until after #4063.