Add repo-standardizer skill: polish any GitHub repo surface (#2715)

* Add repo-standardizer skill: polish any GitHub repo surface

* fix(skill): remove non-string metadata and fix template README refs for vally lint

* docs(skill): drop markdown relative links from README language-switcher example

Vally valid-refs flagged ./README.md and ./README.zh.md as missing file
references; they are generated artifacts, not skill files. Keep the
example as plain text to satisfy the linter.

* fix(template): add missing language switcher to English README template

Align with README.zh.md template and SKILL.md switcher convention:
current language as plain text, other languages as relative links.

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Co-authored-by: programmingWTF <programmingWTF@users.noreply.github.com>

skills/repo-standardizer/templates/ci-node.yml

@@ -0,0 +1,28 @@
+name: CI
+
+on:
+  push:
+    branches: [$default-branch]
+  pull_request:
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node-version: [20, 22]
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: ${{ matrix.node-version }}
+          cache: npm
+      - name: Install dependencies (lockfile-aware)
+        run: |
+          if [ -f package-lock.json ]; then npm ci
+          elif [ -f pnpm-lock.yaml ]; then npm i -g pnpm && pnpm install --frozen-lockfile
+          elif [ -f yarn.lock ]; then npm i -g yarn && yarn install --frozen-lockfile
+          else npm install
+          fi
+      - run: npm run lint --if-present
+      - run: npm test --if-present