ci(docs): bump Node to 22 in docs workflows

chevrotain@12.0.0 (pulled in by vitepress-plugin-mermaid) requires
Node >=22; the previous Node 20 setting caused yarn install to fail.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: auricom

.github/workflows/docs_build.yml

@@ -20,7 +20,7 @@ jobs:
       - name: Setup Node
         uses: actions/setup-node@v6
         with:
-          node-version: 20
+          node-version: 22
           cache: yarn # or pnpm / npm
           cache-dependency-path: docs/yarn.lock
       - name: Install dependencies

.github/workflows/docs_deploy.yml

@@ -35,7 +35,7 @@ jobs:
       - name: Setup Node
         uses: actions/setup-node@v6
         with:
-          node-version: 20
+          node-version: 22
           cache: yarn # or pnpm / npm
           cache-dependency-path: docs/yarn.lock
       - name: Setup Pages

.github/workflows/docs_preview.yml

@@ -28,7 +28,7 @@ jobs:
       - name: Setup Node
         uses: actions/setup-node@v6
         with:
-          node-version: 20
+          node-version: 22
           cache: yarn
           cache-dependency-path: docs/yarn.lock