add docker build to pipeline

.drone.yml

@@ -3,38 +3,35 @@ type: docker
 name: android-build
 
 steps:
-  # Step 1: Build Debug APK
+  - name: build-docker-image
+    image: plugins/docker
+    settings:
+      registry: docker.gutierrezdequevedo.com
+      repo: docker.gutierrezdequevedo.com/ps/mathstuff
+      tags:
+        - latest
+        - ${DRONE_COMMIT_SHA:0:7}
+
   - name: build-debug
     image: cirrusci/android-sdk:33
-    environment:
-      GRADLE_USER_HOME: .gradle
     commands:
       - cd MathHomeworkHelper
       - echo "Building Debug APK..."
-      - chmod +x ./gradlew
-      - ./gradlew clean assembleDebug
+      - gradle clean assembleDebug
       - echo "Debug APK built successfully!"
 
-  # Step 2: Build Release APK
   - name: build-release
     image: cirrusci/android-sdk:33
-    environment:
-      GRADLE_USER_HOME: .gradle
     commands:
       - cd MathHomeworkHelper
       - echo "Building Release APK..."
-      - chmod +x ./gradlew
-      - ./gradlew clean assembleRelease
+      - gradle clean assembleRelease
       - echo "Release APK built successfully!"
 
-  # Step 3: Run Unit Tests
   - name: run-tests
     image: cirrusci/android-sdk:33
-    environment:
-      GRADLE_USER_HOME: .gradle
     commands:
       - cd MathHomeworkHelper
       - echo "Running unit tests..."
-      - chmod +x ./gradlew
-      - ./gradlew test
+      - gradle test
       - echo "Tests completed!"