test: make native runtime review repeatable - #1120

The installed React and Angular runtime fixtures exposed their state as adjacent text and required an ad hoc script for interactive review. This adds labeled state panels, responsive wrapping, and a repeatable node scripts/react-parity/review-runtime.mjs command.

The command prepares isolated installed consumers, checks their declarations, runs all eleven existing browser scenarios, then serves fresh loopback instances for manual review. It keeps source provenance separate from packed artifact hashes and cleans up servers, preparation process groups, and owned temporary files on errors or shutdown. The guide documents the three-read history limit, expected state transitions, and reset procedure.

Validation: 429 focused tests passed; both packed consumers passed all eleven e2e scenarios. Chrome MCP and the in-app browser independently exercised both frameworks through history, tools, protected errors, streaming cancellation, interrupt observation, reuse, and disposal. Each session made three history reads and seven run requests with one handler call, no unexpected requests, and no console warnings/errors. Actual CLI shutdown removed its consumers and closed all review ports. Source/built boundaries and inventory checks passed; independent specification and quality reviews approved the implementation.

Process-cleanup tests use static child scripts with paths passed as data. Cleanup waits for both worker closure and confirmed process-group disappearance; transient macOS permission errors are retried within a fixed deadline, while persistent denial reports failure and retains owned files. Deterministic regressions cover each signal/probe stage and the failure path.

This is a contributor review fixture for the private shared runtime. Production runtime/native implementations are unchanged; public package cutover, full component parity, SSR, and interrupt resume remain outside this increment.