D100 — Community surfaces: Pages from docs/, Discussions on, Wiki off

Decision. Three GitHub surfaces settled at once. Wiki: disabled. Pages: enabled, built by MkDocs Material from docs/ (mkdocs.yml, workflow .github/workflows/docs.yml, mkdocs build --strict) — the markdown in docs/ stays the single source, the site is only a rendering of it. Discussions: enabled, as the place for questions whose answer isn't documentation yet; when an answer stabilizes it is promoted into docs/ through a PR.

Rationale. The wiki is a separate git repo: no PR, no test check, no review, and — decisive here — no way to change it in the same commit as the code, which is the project's central documentation invariant (D98, docs/index.md §Maintenance rules). It would have re-created, in a place nobody diffs, exactly the drift D98 removed. It adds nothing for agents either (they read docs/ from the repo or by raw URL; agent-install.md is already the raw-URL-safe runbook, D97), and it would put runbooks that run curl … | sh and handle tokens somewhere editable without review. Pages gives the readability a wiki promises without giving up the PR flow.

Consequences. --strict makes a broken internal link a build failure, so moving a page breaks CI instead of the published site: the two ../ links out of docs/ (config.example.yaml, test/e2e/README.md) became absolute GitHub URLs. The nav in mkdocs.yml mirrors the grouping of docs/index.md, which remains the canonical map — a new page goes in both.