chore(ci): add wiki-lint to CI for parity with ci-checks.sh

scripts/ci-checks.sh runs five gates; .forgejo/workflows/ci.yml ran only four
— wiki-lint --strict was missing. quality-gates.md states "ci.yml encodes the
same checks" as local, which was not quite true. Add the wiki-lint step to the
markdown job so CI matches local the day a runner is registered.

wiki-lint is pure POSIX sh (grep/awk/sed/find), so it runs in the existing
node:20 container — no new image or job.

This does not by itself stop drift reaching main: as quality-gates.md notes,
no Forgejo Actions runner is registered, so nothing enforces CI server-side
today. The local pre-push hook remains the active enforcement layer; this
change ensures CI is ready to take over once a runner exists. Verified
wiki-lint passes clean on main (137 pass / 0 fail).

(Sam & Claude)

.forgejo/workflows/ci.yml

@@ -39,6 +39,12 @@ jobs:
       - uses: actions/checkout@v4
       - name: Markdown format gate
         run: ./scripts/check-format.sh
+      # Keep CI in parity with scripts/ci-checks.sh, which also runs wiki-lint.
+      # Pure POSIX sh (grep/awk/sed/find) — runs in the node:20 container.
+      # quality-gates.md claims CI encodes the same checks as local; this makes
+      # that true. (CI still only enforces once a Forgejo runner is registered.)
+      - name: Wiki lint (dangling refs, orphan pages, resurrected names)
+        run: ./scripts/wiki-lint --strict
 
   port:
     runs-on: ubuntu-latest