Crash reporting and observability

Makes an Expo app report its crashes to Sentry through one port and one adapter, plugged into the canonical root skeleton as a root kit (one registry entry, no root file edited): nothing leaves the device before the person's choice, nothing personal leaves at all, every error reaches exactly one issue, and every store build and OTA update can be read in TypeScript source. One zero-dependency checker proves it on the real code and configs.

Rules that must hold