fix: cache Maven wrapper binary to prevent transient CI failures

[Copilot]

The check-vue CI job (vue-default-additional) failed with a transient wget error downloading apache-maven-3.9.16-bin.zip from Maven Central during build-jhipster-bom. The root cause: ~/.m2/wrapper/dists (Maven wrapper binary) was never cached — only ~/.m2/repository was — so every CI run required a live download from Maven Central.

Changes

• vue.yml, angular.yml, react.yml: Add actions/cache@v4 for ~/.m2/wrapper/dists immediately after setup-runner. On cache hit the Maven wrapper binary is already present; on miss it downloads once and saves for subsequent runs.

• .github/actions/build-cache/action.yml: Add the same actions/cache@v4 step before cache-java-dependencies so the nightly cache build also warms this cache.

Cache key uses hashFiles on the Maven wrapper properties template to invalidate automatically when the Maven version is bumped:

- uses: actions/cache@v4
  with:
    path: ~/.m2/wrapper/dists
    key: ${{ runner.os }}-jhipster-mvnw-${{ hashFiles('generator-jhipster/generators/java-simple-application/generators/maven/templates/.mvn/wrapper/maven-wrapper.properties') }}