ci: Add Android CI workflow with Gradle build

Sets up GitHub Actions to build the Android project on push and pull request to the main branch. Includes JDK 21 setup and API key handling via secrets.

Author: ArtemZarubin

.github/workflows/android.yml

@@ -0,0 +1,32 @@
+name: Android CI
+
+on:
+  push:
+    branches: [ "master" ]
+  pull_request:
+    branches: [ "master" ]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v4
+    - name: set up JDK 21
+      uses: actions/setup-java@v4
+      with:
+        java-version: '21'
+        distribution: 'temurin'
+        cache: gradle
+
+    - name: Grant execute permission for gradlew
+      run: chmod +x gradlew
+
+    - name: Create local.properties with API keys
+      run: |
+        echo "OPEN_WEATHER_API_KEY=${{ secrets.OPEN_WEATHER_API_KEY }}" > ./local.properties
+        echo "GEOAPIFY_API_KEY=${{ secrets.GEOAPIFY_API_KEY }}" >> ./local.properties
+      
+    - name: Build with Gradle
+      run: ./gradlew build