Finalize ProChat website quality pass

[stevewesthoek]

Summary

• Preserve cinematic frame continuity through cache transitions and bidirectional scroll; add deterministic reversal evidence.
• Keep utility routes (Contact, Docs, Privacy, Terms) within the shared cinematic identity with restrained static atmospheric media and no legacy footer.
• Record the current architecture, measured glass evaluation, deployment state, and remaining performance/security roadmap items.

Validation

• TypeScript, ESLint, design lint, asset validator (56 tests), asset validation, and documentation links pass.
• Production build and focused Playwright route/scroll/reduced-motion/responsive evidence passed on this head in local verification.
• Manual system-Chrome reverse-scroll checks showed continuous painted frames, over 500 distinct rendered outputs per route, and no console errors.

Production deployment is handled by the repository normal main workflow after this PR is merged.