PERF.53 Apps: 29.6 MB of byte-identical files under different URLs across the eight releases, and every new release re-downloads 98 % unchanged files

tools/perf/addons-shared.mjs hashed every file of the eight current releases: 665 distinct contents under 2,163 URLs, 29.6 MB extra on the wire for a person who opens more than one app (cabinetcraft add-on in four apps 5.8 MB, dwg/ 3.0 MB, ifc schemas in four apps 2.3 MB, regs in four 2.3 MB, m3d 1.3 MB, crs-db.json 914 KB three times, host.js / addons.js / libitem.js eight times). Across releases: CadCraft 0.8.1 → 0.8.2 kept 2,084 of 2,127 files byte-identical (158 MB) and every one is re-downloaded under the new version URL; the same for every app and every "Save for offline" re-save (PERF.15). Vendor libraries are fine (one URL each, pinCurrent works). Change: a shared /assets/lib/<name>/<content-hash>/ URL for lib/* copies and shared add-ons (release-app.php pins it like vendor paths; the import map aliases ./dwg/x.js to it), or content-hashed file names so an unchanged file keeps its URL across releases. Both shrink the import map, which lists every file because ?v= busting needs an entry per module (499 entries / 48 KB in CadCraft, 772 / 78 KB in BimCraft per page view; AppBuilds.php:391-397).