ci: bump all workflows to Node 22

mermaid@11 pulls chevrotain@12 which requires Node >=22. Node 22 is
LTS and matches local dev environment.

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

Author: sirdeggen

.github/workflows/ci.yml

@@ -12,7 +12,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        node-version: [20.x]
+        node-version: [22.x]
 
     steps:
       - uses: actions/checkout@v6
@@ -53,7 +53,7 @@ jobs:
       - uses: pnpm/action-setup@v6
       - uses: actions/setup-node@v6
         with:
-          node-version: 20
+          node-version: 22
           cache: pnpm
 
       - run: pnpm install --ignore-scripts

.github/workflows/codegen.yml

@@ -49,7 +49,7 @@ jobs:
       # ── TypeScript types (openapi-typescript) ────────────────────────────
       - uses: actions/setup-node@v6
         with:
-          node-version: '20'
+          node-version: '22'
       - name: Generate TS types from overlay spec
         run: |
           mkdir -p conformance/generated/overlay

.github/workflows/conformance.yml

@@ -13,7 +13,7 @@ jobs:
       - uses: actions/checkout@v6
       - uses: actions/setup-node@v6
         with:
-          node-version: '20'
+          node-version: '22'
       - uses: pnpm/action-setup@v6
       - name: Install deps
         run: pnpm install --no-frozen-lockfile

.github/workflows/docs-deploy.yml

@@ -32,7 +32,7 @@ jobs:
 
       - uses: actions/setup-node@v4
         with:
-          node-version: '20'
+          node-version: '22'
           cache: 'pnpm'
 
       - name: Install dependencies

.github/workflows/release.yml

@@ -20,7 +20,7 @@ jobs:
 
       - uses: actions/setup-node@v6
         with:
-          node-version: 20
+          node-version: 22
           registry-url: https://registry.npmjs.org
           cache: pnpm