PERF.14 Lab: every /lab app page walks the a Discord member folder three times (181 ms of PHP, 2,938 files stat-ed)

Measured 2026-11-08 in-process for /lab/cadcraft: 181 ms of PHP: AppBuilds::headTags 34 ms (jsFilesDeep + filemtime of every a Discord member file for the import map's ?v=), devStamp 37 ms (path|size|mtime of every a Discord member file plus the shell), offlineFiles 22 ms + offline_size 42 ms (2,938 files), Lang 20 ms; the HTML is 1,039 KB (import map 105 KB, cc-lang 590 KB). Staff and lab testers only, and the lab deliberately never caches (Clear-Site-Data), so every reload pays it.

Plan: one directory walk per request shared by headTags, devStamp and offlineFiles (a small in-request cache of [path, size, mtime]); PERF.2 and PERF.3 take the inline catalog and the offline list out of the page. Target under 60 ms.