#99 — Lighthouse CI budgets (split from #38 perf pass)

The one deliberately-unshipped piece of the #38 performance pass: Lighthouse CI runs against the routes named in docs/qa/performance-budget.md, failing under the Web-Vitals budgets there. Needs a served build in CI (self-hosted runners share the dev stack — port + resource plan required). The bundle-size regression gate (scripts/bundle-budget.mjs) already ships and runs non-gating in the CI build job; this card is only the Lighthouse layer. Source: #38, split 2026-07-09 by Agent A.