start kotlin/jetpack compose rewrite

replace the flutter project with a gradle/compose android app:
- nix flake dev shell (jdk21, android sdk 35, build-tools 37, gradle)
- material3 app with a placeholder screen
- roborazzi/robolectric screenshot tests with one golden
- carry over the existing launcher/notification assets

.github/workflows/build-flutter-release.yml

@@ -1,78 +0,0 @@
-name: build-flutter-release
-
-on:
-  push:
-    tags: ['v*']
-
-jobs:
-  build-apk:
-    runs-on: ubuntu-22.04
-    steps:
-      - uses: actions/checkout@v3
-
-      - name: Get subtracks version
-        run: echo "SUBTRACKS_VERSION=$(yq '.version' pubspec.yaml | cut -d '+' -f 1)" >> $GITHUB_ENV
-
-      - uses: subosito/flutter-action@v2
-        with:
-          flutter-version: '3.7.11'
-          channel: 'stable'
-          cache: true
-
-      - run: cp .env.example .env
-      - run: flutter pub get
-
-      - name: Retrieve subtracks.keystore
-        env:
-          SUBTRACKS_KEYSTORE_BASE64: ${{ secrets.SUBTRACKS_KEYSTORE_BASE64 }}
-        run: |
-          echo "$SUBTRACKS_KEYSTORE_BASE64" | base64 --decode > android/subtracks.keystore
-      - name: Retrieve key.properties
-        env:
-          SUBTRACKS_KEYPROPERTIES_BASE64: ${{ secrets.SUBTRACKS_KEYPROPERTIES_BASE64 }}
-        run: |
-          echo "$SUBTRACKS_KEYPROPERTIES_BASE64" | base64 --decode > android/key.properties
-      
-      - run: flutter build apk -PsignRelease
-
-      - run: mv build/app/outputs/flutter-apk/app-release.apk subtracks-${SUBTRACKS_VERSION}.apk
-      - uses: actions/upload-artifact@v3
-        with:
-          name: subtracks-release-apk
-          path: subtracks-*.apk
-
-  build-aab:
-    runs-on: ubuntu-22.04
-    steps:
-      - uses: actions/checkout@v3
-
-      - name: Get subtracks version
-        run: echo "SUBTRACKS_VERSION=$(yq '.version' pubspec.yaml)" >> $GITHUB_ENV
-
-      - uses: subosito/flutter-action@v2
-        with:
-          flutter-version: '3.7.11'
-          channel: 'stable'
-          cache: true
-
-      - run: cp .env.example .env
-      - run: flutter pub get
-
-      - name: Retrieve subtracks.keystore
-        env:
-          SUBTRACKS_KEYSTORE_BASE64: ${{ secrets.SUBTRACKS_KEYSTORE_BASE64 }}
-        run: |
-          echo "$SUBTRACKS_KEYSTORE_BASE64" | base64 --decode > android/subtracks.keystore
-      - name: Retrieve key.properties
-        env:
-          SUBTRACKS_KEYPROPERTIES_BASE64: ${{ secrets.SUBTRACKS_KEYPROPERTIES_BASE64 }}
-        run: |
-          echo "$SUBTRACKS_KEYPROPERTIES_BASE64" | base64 --decode > android/key.properties
-
-      - run: flutter build appbundle -PsignRelease
-
-      - run: mv build/app/outputs/bundle/release/app-release.aab subtracks-${SUBTRACKS_VERSION}.aab
-      - uses: actions/upload-artifact@v3
-        with:
-          name: subtracks-release-aab
-          path: subtracks-*.aab

.github/workflows/build-flutter.yml

@@ -1,30 +0,0 @@
-name: build-flutter
-
-on:
-  push:
-    branches: ['main']
-  pull_request:
-    branches: ['main']
-
-jobs:
-  build-apk:
-    runs-on: ubuntu-22.04
-    steps:
-      - uses: actions/checkout@v3
-
-      - uses: subosito/flutter-action@v2
-        with:
-          flutter-version: '3.7.11'
-          channel: 'stable'
-          cache: true
-
-      - run: cp .env.example .env
-      - run: flutter pub get
-      - run: flutter analyze
-      - run: flutter build apk
-
-      - run: mv build/app/outputs/flutter-apk/app-release.apk subtracks-$(git rev-parse --short HEAD).apk
-      - uses: actions/upload-artifact@v3
-        with:
-          name: subtracks-testing
-          path: subtracks-*.apk