Further fixes for selected Node.js versions and related CI errors (#3265)

## Summary
- The project's `engines` field was recently downgraded from Node 22
back to `>=20.18.3` (PR #3260), but CI workflows were left on Node 22
(or 23).
- The `Refresh WordPress Major&Beta` and `Refresh SQLite plugin`
workflows were on Node 23 which is outside
`@jest/diff-sequences@30.0.1`'s supported range, causing `npm ci` to
fail with `EBADENGINE`. See [failing
run](https://github.com/WordPress/wordpress-playground/actions/runs/21956463286).
- Switches all workflows to Node 20 (the `prepare-playground` default)
unless they specifically need a later version:
- **Keep Node 22**: `test-playground-cli`, `test-built-npm-packages`,
`test-running-unbuilt-playground-cli` (need
`--experimental-strip-types`)
- **Keep Node 24**: `test-unit-jspi`, `test-redis-extension`,
`test-memcached-extension` (need JSPI)
- **Downgraded to 20**: `test-unit-asyncify`, `build`,
`test-php-wasm-cli-smoke`, `refresh-wordpress-major-and-beta`,
`refresh-sqlite-integration`, `refresh-wordpress-nightly`,
`publish-npm-packages`
- Aligns `engines` field (`node >=20.10.0`, `npm >=10.2.3`) across all
packages with
[wordpress-develop](https://github.com/WordPress/wordpress-develop/blob/trunk/package.json)
to match WordPress core requirements
- Updates `.nvmrc` from `v20.18.3` to `20` (major version only)
- Adds a CI check (`tools/check-node-engine-alignment.sh`) to the
`lint-and-typecheck` job that fetches WordPress Core's `engines.node`
and `engines.npm` from `wordpress-develop/trunk/package.json` and
verifies all local package.json files declare the same values,
preventing future drift

## Test plan
- [x] CI passes on this PR
- [ ] Verify scheduled workflows (`Refresh WordPress Major&Beta`,
`Refresh SQLite plugin`, `Refresh WordPress Nightly`) pass after merge

Note: This PR was created with the assistance of Claude Code.

Author: brandonpayton

.github/workflows/ci.yml

@@ -25,6 +25,7 @@ jobs:
             - run: npx nx affected --target=lint
             - run: npx nx affected --target=typecheck
             - run: npx nx check-orphan-pages docs-site
+            - run: bash tools/check-node-engine-alignment.sh
     test-unit-asyncify:
         runs-on: ubuntu-latest
         strategy:
@@ -69,7 +70,7 @@ jobs:
                   submodules: true
             - uses: ./.github/actions/prepare-playground
               with:
-                  node-version: 22
+                  node-version: 20
             - run: node --expose-gc node_modules/nx/bin/nx affected --target=${{ matrix.target }}
               env:
                   MYSQL_DATABASE: test_db
@@ -328,7 +329,7 @@ jobs:
                   submodules: true
             - uses: ./.github/actions/prepare-playground
               with:
-                  node-version: 22
+                  node-version: 20
             - run: packages/php-wasm/cli/tests/smoke-test.sh
 
     # Redis extension tests - verifies the php-redis extension loads
@@ -392,7 +393,7 @@ jobs:
                   submodules: true
             - uses: ./.github/actions/prepare-playground
               with:
-                  node-version: 22
+                  node-version: 20
             - run: |
                   if ADDITIONAL_REMOTE_ORIGINS=invalid-origin npx nx build playground-client; then
                     echo "The Playground client build should have failed due to an invalid additional origin."

.github/workflows/publish-npm-packages.yml

@@ -66,7 +66,7 @@ jobs:
             - name: Set up Node.js with OIDC
               uses: actions/setup-node@v4
               with:
-                  node-version: '22'
+                  node-version: '20'
                   registry-url: 'https://registry.npmjs.org'
                   cache: 'npm'
 

.github/workflows/refresh-sqlite-integration.yml

@@ -35,7 +35,7 @@ jobs:
                   submodules: true
             - uses: ./.github/actions/prepare-playground
               with:
-                  node-version: 23
+                  node-version: 20
             - name: 'Refresh the SQLite bundle'
               shell: bash
               run: npx nx bundle-sqlite-database playground-wordpress-builds

.github/workflows/refresh-wordpress-major-and-beta.yml

@@ -40,7 +40,7 @@ jobs:
                   submodules: true
             - uses: ./.github/actions/prepare-playground
               with:
-                  node-version: 23
+                  node-version: 20
             - name: 'Recompile WordPress'
               id: build
               shell: bash

.github/workflows/refresh-wordpress-nightly.yml

@@ -33,7 +33,7 @@ jobs:
                   submodules: true
             - uses: ./.github/actions/prepare-playground
               with:
-                  node-version: 22
+                  node-version: 20
             - name: 'Recompile WordPress'
               shell: bash
               run: npx nx bundle-wordpress:nightly playground-wordpress-builds

.nvmrc

@@ -1 +1 @@
-v20.18.3
+20