Point CI at my-app instead of the create-react-app monorepo (#4)

Removes the inherited upstream create-react-app CI (build-and-test.yml,
e2e-base.yml, lint.yml), which exercised packages/ through lerna, verdaccio and
puppeteer on Node 16 and could not pass after commit dc079b1 replaced the
monorepo root package.json with a create-react-app app's.

Retargets node.js.yml at my-app, running install, lint and build on Node 20.x
and 22.x. The 18.x leg is dropped because Vite 8 requires ^20.19.0 || >=22.12.0.

This also gives my-app its first pull request coverage; deploy-my-app.yml only
runs on main, so its code was previously never built or linted before reaching
the default branch.

Author: niteeshkanna-sh

.github/workflows/build-and-test.yml

@@ -1,31 +1,44 @@
-# This workflow will do a clean installation of node dependencies, cache/restore them, build the source code and run tests across different versions of node
-# For more information see: https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-nodejs
-
+# CI for my-app, the app this repo actively maintains.
+#
+# This previously ran npm ci / build / test at the repo root. That could not
+# pass: the root package.json describes a create-react-app app with no src/ or
+# public/ directory, so react-scripts build always failed looking for
+# public/index.html.
 name: Node.js CI
 
 on:
   push:
-    branches: [ "main" ]
+    branches: ['main']
   pull_request:
-    branches: [ "main" ]
+    branches: ['main']
 
 jobs:
   build:
-
     runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: my-app
 
     strategy:
+      fail-fast: false
       matrix:
-        node-version: [18.x, 20.x, 22.x]
-        # See supported Node.js release schedule at https://nodejs.org/en/about/releases/
+        # Vite 8 requires ^20.19.0 || >=22.12.0, so 18.x is not supported.
+        node-version: [20.x, 22.x]
 
     steps:
-    - uses: actions/checkout@v4
-    - name: Use Node.js ${{ matrix.node-version }}
-      uses: actions/setup-node@v4
-      with:
-        node-version: ${{ matrix.node-version }}
-        cache: 'npm'
-    - run: npm ci
-    - run: npm run build --if-present
-    - run: npm test
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: ${{ matrix.node-version }}
+          cache: npm
+          cache-dependency-path: my-app/package-lock.json
+
+      - name: Install
+        run: npm ci
+
+      - name: Lint
+        run: npm run lint
+
+      - name: Build
+        run: npm run build