Update trusted server documentation for September 2026 release #1038

Description

Update Trusted Server documentation across all surfaces for the August 2026 release.

A full-surface audit (VitePress site, root/crate markdown, in-code docs, config templates) found systemic drift: fabricated/dead content (nonexistent endpoints, Equativ, removed config keys), incomplete references (5 of 15 Settings sections undocumented, 7 of 14 integrations missing from the overview), missing coverage (no Cloudflare/Spin/Axum deployment guides, no telemetry/tsjs/EdgeZero pages, 7 of 10 crates without READMEs), publishing hygiene (75 internal spec/plan files published to the public site, sensitive values in fastly.toml), and zero CI enforcement of doc correctness.

Design spec: docs/superpowers/specs/2026-08-19-documentation-refresh-design.md (PR #1049, branch spec-docs-refresh), including per-surface source-of-truth map, full audit finding index with file:line citations, and ground-truth inventories (routes, config sections, integration capability matrix, CLI tree).

Work packages (all land in PR #1049 together with the spec, one commit per package)

• WP1: Publishing and policy hygiene (srcExclude, CNAME, fastly.toml sensitive values, empty /guide/ page, slash-command/PR-template gate alignment)
• WP2: Remove fabricated and dead content (dead endpoints, Equativ, RequestWrapper, GAM/Kargo pages, auction README rot, FAQ_POC.md, CHANGELOG/.env.example repairs)
• WP3: Configuration reference completion (trusted-server.example.toml + configuration.md parity with all 15 Settings sections and 14 integration configs)
• WP4: API reference rebuild from adapter route tables with per-adapter availability matrix
• WP5: New coverage pages and navigation repair (deployment guides, EdgeZero, telemetry/Tinybird, tsjs, GPT handoff, adserver_mock; un-orphan real integration pages; TESTING.md rewrite)
• WP6: Root markdown and crate READMEs (README/CONTRIBUTING refresh, READMEs for 7 crates, governance corrections)
• WP7: In-code documentation (core module index, platform/ docs, crate headers, key module docs, tsjs JSDoc)
• WP8: Enforcement (docs build on PRs, cargo doc -D warnings in CI, doctests actually running, dependabot gaps)

Absorbed issues

PR #1049 also resolves #277 (nonexistent .with_asset in integration docs, folded into WP2) and #341 (script_guard coverage in the integration guide, folded into WP5).

Done when

• Every endpoint, config key, command, and code path named in documentation exists in code on main, with adapter-specific availability stated.
• Every shipped surface is documented: all 14 integration IDs, 15 config sections, 4 deployment targets, all ts commands, telemetry, tsjs.
• The public docs site publishes only intended pages; no sensitive real-world values remain in tracked config.
• CI fails on dead docs links, broken intra-doc links, and failing doctests.

Affected area

Documentation