Performance budgets

Keeps an Expo app inside budgets that live in one checked-in file: cold start measured from process start, hitch rate and p95 frame time, draw calls per frame, canvases per screen, the per-change storage write, bundle size per platform and memory. The numbers come from Release builds on real iPhones and Android phones, from simulators and emulators (regressions only) and from Jest (fast guards); four zero-dependency checkers judge the code, the budgets, the device reports and the bundles.

Rules that must hold