docs: specify static Hugo website rebuild

[projectious]

Summary

Adds the implementation-ready specification for rebuilding projectious.work as a
static Hugo publication and evidence site.

Issue evaluation

• projectious-work/internal#9 is treated as the governing coordination issue.
• projectious-work/internal#7 is the earlier, compatible migration and content
  requirements issue.
• The specification consolidates both into one website contract.

Key decisions

• Replace the current Reflex site with a static Hugo site deployed to Cloudflare
  Pages.
• Consume an exact-pinned or vendored release of the first-party brand module.
• Center the information architecture on Home, Work, Writing, and About, with an
  optional Now page.
• Present Projectious as an independently led initiative and public workbench,
  not as an established consultancy with unsupported client or production claims.
• Define evidence, maturity, limitations, taxonomy, SEO, accessibility,
  performance, local validation, migration, preview, cutover, and rollback.
• Keep future commercial activation staged and owner-reviewed.

Validation

• git diff --check
• Markdown non-exempt lines checked against the company 80-column convention
• Documentation-only change; no runtime build applies

Process records

• WorkItem: BACK-20260808_1947-VastTide-deliver-website-hugo-rebuild-specification
• Decision: DEC-20260808_1947-SmartSky-rebuild-projectious-work-as-an-evidence

Closes projectious-work/internal#7
Closes projectious-work/internal#9