qa: export one evidence bundle per app playtest

[100yenadmin]

Summary

Add an evidence exporter that turns a built-app playtest into one handoff-ready artifact folder under /Volumes/LEXAR/Codex.

Interface

qa/export_app_evidence.py --app-status-url <url> --out <dir>

Evidence bundle contents

• screenshots
• app-status snapshots
• session surface snapshot
• chat log excerpt/full path copy when available
• move log excerpt/full path copy when available
• provider trace summary
• console/network logs
• build SHA and version
• art-root status
• failure bucket and detail when present

Acceptance criteria

• Output defaults to /Volumes/LEXAR/Codex for Codex artifacts.
• Exporter never writes repo-tracked files unless explicitly pointed at a repo path.
• Missing optional files are represented as evidence gaps, not crashes.
• JSON manifest names every captured file and every missing source.

[100yenadmin]

Evidence exporter draft is up in #490, stacked on #488. It adds qa/export_app_evidence.py with --app-status-url and --out, and captures app-status/session-surface, chat/moves/transcript, run-dir screenshots, console/network/action logs, app-status snapshots, build/art status, provider trace summary, and transition failure bucket.

[100yenadmin]

Initial read-only evidence exporter is consolidated into PR #475 (draft #490 closed as superseded). qa/export_app_evidence.py exports app-status, session-surface, chat/moves/transcript copies, transition metadata, build/art/live summary, and evidence gaps; the clean app proof exported app-evidence/manifest.json under /Volumes/LEXAR/Codex/worldos-built-app-playtest/codex-app-headproof-20260601T043909/. Keep open until PR #475 merges; full screenshots/a11y/console/network bundling can continue as follow-up if needed.