Static Hermes WASM SDK (latest build)

Rewrite README, Features, add React Native and branches docs

The quick start commands were run against a fresh build on Linux.

Bring Features.md up to date with the engine

Every claim was checked by running the built binary, including the ones
left in place. TDZ moves to supported-but-off-by-default: the checks
exist behind -Xenable-tdz, and by default a read before initialization
yields undefined rather than throwing.

Intl is demoted from supported to excluded, per discussion #1211.
CommonJS is not mentioned at all; -commonjs currently aborts in IRGen,
which is now tracked separately.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011S1Txdi8S1K1fkrMP8okq5