Centralize Node.js version selection on 24.22.1 (#57168)

## What changed

- Add `.nvmrc` pinning Node.js to `24.22.1` and raise the root package's minimum Node.js version to match.
- Use `.nvmrc` in repository checks, SDK CI, and npm packaging and publishing workflows.
- Update MCP conformance instructions to use the repository's pinned Node.js version.

GitOrigin-RevId: d864875e538de2b99df73e5a03fc870ce0f90cf0

.github/workflows/repo-checks.yml

@@ -57,7 +57,7 @@ jobs:
       - name: Setup Node.js
         uses: actions/setup-node@53b83947a5a98c8d113130e565377fae1a50d02f # v6.3.0
         with:
-          node-version: 22
+          node-version-file: .nvmrc
 
       - name: Install dependencies
         run: pnpm install --frozen-lockfile

.github/workflows/rust-release.yml

@@ -1579,7 +1579,7 @@ jobs:
       - name: Setup Node.js for npm packaging
         uses: actions/setup-node@53b83947a5a98c8d113130e565377fae1a50d02f # v6.3.0
         with:
-          node-version: 22
+          node-version-file: .nvmrc
 
       - name: Install dependencies
         run: pnpm install --frozen-lockfile
@@ -1893,8 +1893,8 @@ jobs:
       - name: Setup Node.js
         uses: actions/setup-node@53b83947a5a98c8d113130e565377fae1a50d02f # v6.3.0
         with:
-          # Node 24 bundles npm >= 11.5.1, which trusted publishing requires.
-          node-version: 24
+          # Trusted publishing requires the selected Node.js release to include npm >= 11.5.1.
+          node-version-file: .nvmrc
           registry-url: "https://registry.npmjs.org"
           scope: "@openai"
 

.github/workflows/sdk.yml

@@ -64,7 +64,7 @@ jobs:
       - name: Setup Node.js
         uses: actions/setup-node@53b83947a5a98c8d113130e565377fae1a50d02f # v6.3.0
         with:
-          node-version: 22
+          node-version-file: .nvmrc
           cache: pnpm
 
       - name: Prepare Bazel CI