PERF.1 HTTP/2 for getcadcraft.com: Apache runs mpm_prefork + mod_php, so every app start is 140 to 520 requests over HTTP/1.1

Measured 2026-11-08 (tools/perf/startup.mjs, localhost): a cold /use start fetches cadcraft 398 requests / 2.6 MB (233 JS modules), bimcraft 521 / 3.8 MB, partcraft 371 / 3.2 MB, civilcraft 313, modelcraft 238, detailcraft 185, markupcraft 159, takeoffcraft 141. All over HTTP/1.1: Apache is mpm_prefork with mod_php, and mod_http2 cannot run under prefork. A browser opens 6 connections per host, so for a visitor with a 70 ms round trip the request count alone is about 400/6 x 70 ms = 4.5 s before any module runs; on localhost the same start takes 1.2 s.

The fix is a server change, not code: mpm_event + php-fpm 8.3 (installed at /usr/sbin/php-fpm8.3, not in use) + Protocols h2 http/1.1. The VPS serves about 80 virtual hosts from the same Apache, every one on mod_php today, so this needs the owner's go, a maintenance window and a rollback plan (keep the prefork config). Expected: one connection, all modules multiplexed, start time near the localhost figure plus one RTT per import depth. Alternatives rejected: bundling the releases (add-ons import the apps' modules by URL; a bundle would run two copies), a CDN for app files (same request count).

Decision needed: go / not now.