wiki: add pre-commit hook — block new articles missing from SUMMARY.md

The hook fails any commit that adds (or renames) a .md article without a
matching SUMMARY.md entry, addressing the recurring 'article exists but
isn't navigable' drift. Excludes meta files (README/index/SUMMARY,
category index.md, MajorWiki-Deploy-Status). Bypass with --no-verify.

Hook lives in .githooks/ (tracked). Each clone needs:
  git config core.hooksPath .githooks

Companion wrapper ~/bin/wiki-commit (workstation-only, not in repo) does
pull --rebase --autostash + add -A + commit + push so cowork pushes
don't surprise.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.githooks/pre-commit

@@ -0,0 +1,36 @@
+#!/usr/bin/env bash
+# pre-commit — fail if a newly-added article is not linked from SUMMARY.md.
+# Bypass with `git commit --no-verify` if you genuinely need to.
+set -euo pipefail
+
+# Articles being added or renamed in this commit (excludes meta/index/README/SUMMARY/MajorWiki-Deploy-Status, and any */index.md).
+added=$(git diff --cached --name-only --diff-filter=AR -- '*.md' \
+  | grep -vE '^(README|index|SUMMARY|MajorWiki-Deploy-Status)\.md$|/index\.md$' \
+  || true)
+
+[ -z "$added" ] && exit 0
+
+# Read the staged SUMMARY.md if it's part of the commit; otherwise the working-tree copy.
+if git diff --cached --name-only | grep -q '^SUMMARY\.md$'; then
+  summary=$(git show :SUMMARY.md)
+else
+  summary=$(cat SUMMARY.md)
+fi
+
+missing=()
+while IFS= read -r article; do
+  [ -z "$article" ] && continue
+  if ! grep -qF -- "$article" <<<"$summary"; then
+    missing+=("$article")
+  fi
+done <<<"$added"
+
+if [ ${#missing[@]} -gt 0 ]; then
+  echo "✗ pre-commit: new article(s) not linked from SUMMARY.md:" >&2
+  printf '    %s\n' "${missing[@]}" >&2
+  echo "" >&2
+  echo "Add a SUMMARY.md entry for each, or use 'git commit --no-verify' to bypass." >&2
+  exit 1
+fi
+
+exit 0