perf-budget-checklisted

# Perf Budget Check ## Purpose Gate a PR on performance: pull Core Web Vitals (LCP, INP, CLS) and bundle-size measurements for the head ref, compare against the project's declared budget AND against `main`, and emit a pass/fail report. Used by `performance-engineer` and the frontend build pipeline to keep regressions out of `main`. ## Scope - Reads the perf budget from `perf-budget.yaml` (default at repo root; configurable with `--budget`). - Reads a Lighthouse / WebPageTest / RUM-export JSON report for the head ref (path via `--report`, default `work/current/perf/head.json`). - Optionally reads the same report shape for `--base` (`work/current/perf/base.json`); if absent, falls back to budget-only comparison. - Walks `dist/` (or the configured build output) for bundle-size diff against `--base`'s build. - Emits a markdown report and exits non-zero on any budget breach. ## When to use - As a CI gate on every PR that touches `web/`, `app/`, or the build config. - Before a release, against `main` vs the last release tag, to confirm release-on-release perf hasn't drifted. - Manually, when a developer suspects a recent change made the app feel slower. ## When NOT to use - For server-side latency (p50/p99 API). That's a separate skill; use the project's APM dashboard or `loadtest-baseline`. - On a non-production-like build. Lighthouse on a `dev` build is meaningless — the skill refuses to run if `NODE_ENV != production` in the report metadata. - For