chore: add quality gates

.github/CODEOWNERS

@@ -1,2 +1,3 @@
 # Default ownership
 * @maintainers
+README.md @maintainers

.github/workflows/link-check.yml

@@ -0,0 +1,15 @@
+name: Link Check
+on:
+  pull_request:
+    paths: ['**/*.md']
+permissions:
+  contents: read
+  pull-requests: write
+jobs:
+  lychee:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: lycheeverse/lychee-action@v1
+        with:
+          args: --verbose --no-progress --require-https --max-redirects 5 --retry-wait-time 2 --timeout 20s --exclude-private true **/*.md

.github/workflows/md-quality.yml

@@ -0,0 +1,24 @@
+name: Markdown Quality
+on:
+  pull_request:
+    paths: ['**/*.md']
+jobs:
+  quality:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Setup Node
+        uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+      - run: npm i -g textlint @textlint/markdown textlint-rule-terminology textlint-rule-no-dead-link
+      - run: |
+          cat > .textlintrc.json <<'JSON'
+          {
+            "rules": {
+              "terminology": true,
+              "no-dead-link": { "checkRelative": true }
+            }
+          }
+          JSON
+      - run: textlint -f pretty-error '**/*.md'

.github/workflows/readme-guard.yml

@@ -0,0 +1,23 @@
+name: README Guard
+on:
+  push:
+    branches: [ main, master ]
+    paths: [ 'README.md' ]
+permissions:
+  contents: write
+  pull-requests: write
+jobs:
+  guard:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Create review PR for README change
+        uses: peter-evans/create-pull-request@v6
+        with:
+          title: "Guard: Review README.md change"
+          body: "Automated guard: Please review README changes."
+          commit-message: "chore: guard README change"
+          branch: "chore/readme-guard-${{ github.run_id }}"
+          base: "${{ github.ref_name }}"
+          add-paths: |
+            README.md