feat(android): initial project setup with Gradle, AndroidManifest, and MainActivity

.github/workflows/android-ci.yml

@@ -0,0 +1,28 @@
+name: Android CI
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Set up JDK 17
+        uses: actions/setup-java@v4
+        with:
+          distribution: 'temurin'
+          java-version: '17'
+      - name: Cache Gradle
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.gradle/caches
+            ~/.gradle/wrapper/
+          key: ${{ runner.os }}-gradle-${{ hashFiles('**/*.gradle*', '**/gradle-wrapper.properties') }}
+      - name: Build
+        run: |
+          ./gradlew :app:assembleDebug