docs(v2): site design rollout plan and editorial-portfolio mockup

- 2026-05-19-site-design-rollout-plan.md: cutover plan (8 PRs) preserved
  as a future option, plus a "v2 Parallel Deployment - Shipped" addendum
  documenting the actual architecture that landed.
- mockups/2026-05-19-home-editorial.html: self-contained reference
  rendering of the home page used to validate the visual direction
  before execution.

Author: Sohailm25