feat(newos4-debug): dashboard triage + thread panels, mobile layout, gate error.php

- Triage card reads admin/docs/newos4-triage-latest.json defensively: missing/unreadable
  renders as a warning pill, never as zeros (a zero here reads as "nothing is wrong").
  Freshness pill goes stale past 26h so a dead collector cannot look healthy.
- Maintenance thread merges in-app `feedback` reports (kind=maintenance) with agent
  replies from data/maintenance/replies.json into one chronological view.
- Mobile: <=640px single column, smaller type, .table-scroll wrappers, Type column
  hidden, max-width clamp. verify-mobile.py: 360/390px, light+dark -> ALL VIEWPORTS OK,
  page width == viewport (no horizontal overflow).
- "Last ingest" now uses max(ingested_at) instead of end($errors): after the prune the
  array is not chronological and the header contradicted the triage card by 3 days.
- Auto-refresh only fires while the tab is visible (was an unconditional 30s reload).
- Fixed triage checks parsing: digest ships {exit, findings[]}, not a list of strings —
  the first render fataled on stripos(array). Verified 15,167 B render, 0 PHP errors.

nginx (not in git): error.php added to the admin-gated read regex alongside
stats|errors|clusters|dashboard|agent-replies — error.php?hash= was still serving stacks
to anonymous callers. All six now answer 302 without a session.

0 files changed, 0 insertions, 0 deletions