Add public synthetic Reviewer Sandbox

[chefmrfrizzle]

What changed

• adds the selected Option 1 Valoris Reviewer Sandbox as a static React/Vite interface
• provides four role perspectives and a five-step, ten-minute synthetic evidence walkthrough
• presents supporting and challenging evidence together with bounded ADR packet summaries
• adds a role-aware, session-only review handoff with conflict acknowledgement, blocked decisions, copy, JSON download, and clean reset
• fixes the reported iOS header collision and clipped walkthrough labels
• replaces the focus-only top Perspective affordance with a functional native selector synchronized with the four lower role buttons
• improves warning and evidence-label contrast after an automated accessibility finding
• adds mobile/desktop interaction evidence, regression tests, Vercel configuration, and deployment records

Why

This gives prospective reviewers a safe public interface they can inspect without exposing private materials or introducing production protocol components. The latest correction makes both role-selection entry points behave as users expect on phone and desktop.

Root cause

The top control looked like a dropdown but its click handler only focused the first lower role button. It never changed roleId, so it could not select Cryptography, Identity & IT, or Materials Science.

Safety boundaries

• every fixture datum is DEMO or SYNTHETIC
• cryptographic choices remain BLOCKED_UNVERIFIED
• no backend, authentication, uploads, persistence, executable schemas, workers, payments, or private materials
• no scientific, security, production-readiness, or independence approval is asserted

Validation

• npm run test:sandbox: 9 passed
• npm run build: passed
• npm run test:sites: 4 passed
• repository baseline: passed locally; GitHub exact-head result pending for 806f5c8e
• mobile browser gates: synchronized top/lower role selection at 390×844; longest Materials Science label at 320×800; no overflow
• desktop browser gate: synchronized Identity & IT selection at 1440×1024; no overlap or overflow
• accessibility: final axe WCAG A/AA scan reported zero violations
• production alias: https://valoris-reviewer-sandbox.vercel.app
• promoted production deployment: dpl_HtfKgVR5R9pvhjbxmYm5xkSWrWJK, READY, HTTP 200
• production JS/CSS exactly match the validated preview artifact by SHA-256

Review focus

Please verify the public/static boundary, DEMO/SYNTHETIC labeling, BLOCKED_UNVERIFIED cryptography language, synchronized role-selection behavior, accessible responsive flow, and absence of claims that imply scientific acceptance or independent-person assurance.

This PR is intentionally draft and must not be merged without the repository's normal review and check gates.