Improve supply chain defaults

Pin third-party workflow actions, run CI on Node 26 with npm ci, and add npm minimum release age configuration.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: dgreif

.github/workflows/nodejs.yml

@@ -6,12 +6,12 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10
       - name: Use Node.js
-        uses: actions/setup-node@v5
+        uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e
         with:
-          node-version: '24.x'
-      - run: npm install
+          node-version: '26.x'
+      - run: npm ci
       - run: npm run build --if-present
       - run: npm test
         env:

.github/workflows/publish.yml

@@ -12,10 +12,10 @@ jobs:
   publish-npm:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
-      - uses: actions/setup-node@v5
+      - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10
+      - uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e
         with:
-          node-version: 24
+          node-version: 26
           registry-url: https://registry.npmjs.org/
           cache: npm
       - run: npm ci

.npmrc

@@ -0,0 +1 @@
+min-release-age=3