ci: split android into its own job for graph visibility

The merged test-and-build matrix hid Android behind an OS-keyed matrix
leg, so the workflow graph no longer showed a distinct Android node.
Restore visibility by splitting into two parallel jobs after lint:

- build-desktop (matrix: ubuntu/macos/windows): runs JVM tests for the
  KMP/JVM modules (quartz, commons, cli, desktopApp) and packages the
  native installer per OS.
- test-and-build-android (ubuntu): runs the full test sweep and
  assembleBenchmark, uploads APKs and reports.

Trade-off: Ubuntu spins up two parallel runners instead of one, but
wall time is unchanged and Android is once again a visible node.

.github/workflows/build.yml

@@ -31,7 +31,7 @@ jobs:
       - name: Linter (gradle)
         run: ./gradlew spotlessCheck
 
-  test-and-build:
+  build-desktop:
     needs: lint
     strategy:
       fail-fast: false
@@ -66,22 +66,7 @@ jobs:
           cache: gradle
 
       - name: Test + Build Desktop (gradle)
-        run: ./gradlew test :desktopApp:${{ matrix.desktop-task }} --no-daemon
-
-      - name: Build Android Benchmark APKs (gradle)
-        if: matrix.os == 'ubuntu-latest'
-        run: ./gradlew assembleBenchmark --no-daemon
-
-      - name: Android Test Report
-        uses: asadmansr/android-test-report-action@v1.2.0
-        if: ${{ always() && matrix.os == 'ubuntu-latest' }}
-
-      - name: Upload Test Results
-        uses: actions/upload-artifact@v7
-        if: ${{ always() && matrix.os == 'ubuntu-latest' }}
-        with:
-          name: Test Reports
-          path: amethyst/build/reports
+        run: ./gradlew :quartz:test :commons:test :cli:test :desktopApp:test :desktopApp:${{ matrix.desktop-task }} --no-daemon
 
       - name: Upload Desktop Distribution
         uses: actions/upload-artifact@v7
@@ -89,23 +74,49 @@ jobs:
           name: ${{ matrix.desktop-artifact-name }}
           path: ${{ matrix.desktop-artifact-path }}
 
+  test-and-build-android:
+    needs: lint
+    runs-on: ubuntu-latest
+    timeout-minutes: 60
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v6
+
+      - name: Set up JDK 21
+        uses: actions/setup-java@v5
+        with:
+          distribution: 'zulu'
+          java-version: 21
+          cache: gradle
+
+      - name: Test + Build Android (gradle)
+        run: ./gradlew test assembleBenchmark --no-daemon
+
+      - name: Android Test Report
+        uses: asadmansr/android-test-report-action@v1.2.0
+        if: always()
+
+      - name: Upload Test Results
+        uses: actions/upload-artifact@v7
+        if: always()
+        with:
+          name: Test Reports
+          path: amethyst/build/reports
+
       - name: Upload Play APK Benchmark
         uses: actions/upload-artifact@v7
-        if: matrix.os == 'ubuntu-latest'
         with:
           name: Play Benchmark APK
           path: amethyst/build/outputs/apk/play/benchmark/amethyst-play-universal-benchmark.apk
 
       - name: Upload FDroid APK Benchmark
         uses: actions/upload-artifact@v7
-        if: matrix.os == 'ubuntu-latest'
         with:
           name: FDroid Benchmark APK
           path: amethyst/build/outputs/apk/fdroid/benchmark/amethyst-fdroid-universal-benchmark.apk
 
       - name: Upload Compose Reports
         uses: actions/upload-artifact@v7
-        if: matrix.os == 'ubuntu-latest'
         with:
           name: Compose Reports
           path: amethyst/build/compose_compiler