ci: Add build jobs for android & linux

.github/workflows/build-apps.yml

@@ -0,0 +1,40 @@
+name: Build apps
+on: [push]
+jobs:
+  build-linux:
+    runs-on: ubuntu-24.04
+    defaults:
+      run:
+        working-directory: ./app
+    steps:
+      - name: Clone repository
+        uses: actions/checkout@v4
+      - name: Set up Flutter
+        uses: subosito/flutter-action@v2
+        with:
+          channel: stable
+      - run: |
+          sudo apt-get update -y
+          sudo apt-get install -y ninja-build libgtk-3-dev libcurl4-openssl-dev
+      - run: flutter build linux
+      - name: compress bundle
+        run: tar -cJf pikatorrent-linux.tar.xz ./build/linux/x64/release/bundle/
+      - uses: actions/upload-artifact@v4
+        with:
+          path: /app/pikatorrent-linux.tar.xz
+  build-android:
+    runs-on: ubuntu-24.04
+    defaults:
+      run:
+        working-directory: ./app
+    steps:
+      - name: Clone repository
+        uses: actions/checkout@v4
+      - name: Set up Flutter
+        uses: subosito/flutter-action@v2
+        with:
+          channel: stable
+      - run: flutter build apk
+      - uses: actions/upload-artifact@v4
+        with:
+          path: app/build/app/outputs/apk/release/*