ci: Add Gitea Actions workflow

- Build and test on push/PR to main
- Run unit tests
- Build debug APK
- Run Android lint (non-blocking)
- Upload artifacts (APK + lint reports)

Note: Requires gradle wrapper to be generated with 'gradle wrapper'

.gitea/workflows/ci.yaml

@@ -0,0 +1,64 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up JDK 17
+        uses: actions/setup-java@v4
+        with:
+          java-version: '17'
+          distribution: 'temurin'
+          cache: gradle
+
+      - name: Grant execute permission for gradlew
+        run: chmod +x gradlew
+
+      - name: Run unit tests
+        run: ./gradlew test --stacktrace
+
+      - name: Build debug APK
+        run: ./gradlew assembleDebug --stacktrace
+
+      - name: Upload APK artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: app-debug
+          path: app/build/outputs/apk/debug/app-debug.apk
+          retention-days: 7
+
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up JDK 17
+        uses: actions/setup-java@v4
+        with:
+          java-version: '17'
+          distribution: 'temurin'
+          cache: gradle
+
+      - name: Grant execute permission for gradlew
+        run: chmod +x gradlew
+
+      - name: Run Android Lint
+        run: ./gradlew lint --stacktrace
+        continue-on-error: true
+
+      - name: Upload lint results
+        uses: actions/upload-artifact@v4
+        with:
+          name: lint-results
+          path: app/build/reports/lint-results*.html
+          retention-days: 7