Add full-surface documentation refresh spec

[aram356]

Summary

• Single PR for the full documentation refresh: the design spec plus all eight work packages land here, one commit (or small series) per package, reviewable commit-by-commit.
• The spec was synthesized from a four-track audit of main at 2e85a1cdc (VitePress site, root/crate markdown, in-code docs, config templates), every finding cited at file:line, with ground-truth inventories (routes with per-adapter availability, all 15 Settings sections, 14-integration capability matrix, ts CLI tree) as appendices.

Changes

File	Change
docs/superpowers/specs/2026-08-19-documentation-refresh-design.md	Design spec: audit findings, source-of-truth map, eight work packages, acceptance criteria
WP1 (upcoming commits)	Publishing/policy hygiene: srcExclude, CNAME, fastly.toml sensitive values, empty /guide/ page, gate alignment
WP2	Remove fabricated/dead content: dead endpoints, Equativ, RequestWrapper, .with_asset, GAM/Kargo pages, auction README rot, FAQ_POC.md, CHANGELOG/.env.example repairs
WP3	Config reference parity with all 15 Settings sections and 14 integration configs
WP4	API reference rebuilt from adapter route tables with availability matrix
WP5	New pages: deployment guides, EdgeZero, telemetry/Tinybird, tsjs, GPT handoff, adserver_mock, script guards; nav repair; TESTING.md rewrite
WP6	Root markdown and crate READMEs
WP7	In-code docs: core module index, platform/ docs, crate headers, tsjs JSDoc
WP8	Enforcement: docs build on PRs, cargo doc -D warnings, doctests in CI, dependabot gaps

Closes

Closes #1038
Closes #277
Closes #341

Test plan

• Docs format: cd docs && npm run format (passes on the spec)
• Docs build: cd docs && npm run lint && npm run build (after WP commits land)
• cargo fmt --all -- --check and target-matched clippy/tests for crates touched by WP7
• cargo doc --no-deps warning-free for core and adapters (WP7/WP8)
• Acceptance greps from WP2-WP4 included in this description when work lands
• Other: spec content verified against main at 2e85a1cdc by four parallel read-only audits, then realigned to rc/202608 (new [cache] section, admin EC diagnostics routes, restructured CLI)

Checklist

• Changes follow CLAUDE.md conventions
• No secrets or credentials committed