ci: add release build

Signed-off-by: Harry Chen <i@harrychen.xyz>

.github/workflows/example-app.yml

@@ -1,30 +1,32 @@
-# This is a basic workflow to help you get started with Actions
-
 name: Build Example App
 
-# Controls when the action will run. Triggers the workflow on push or pull request 
-# events but only for the master branch
 on: [push, pull_request]
 
-# A workflow run is made up of one or more jobs that can run sequentially or in parallel
 jobs:
-  # This workflow contains a single job called "build"
   build:
-    # The type of runner that the job will run on
     runs-on: ubuntu-latest
-    if: "!contains(github.event.head_commit.message, 'ci skip')"
+    if: ${{ !contains(github.event.head_commit.message, 'ci skip') }}
+
+    strategy:
+      fail-fast: false
+      matrix:
+        variant: [debug, release]
+        include:
+          - variant: debug
+            artifact-path: build/app/outputs/apk/app-debug.apk
+          - variant: release
+            artifact-path: build/app/outputs/flutter-apk/app-release.apk
 
-    # Steps represent a sequence of tasks that will be executed as part of the job
     steps:
-    # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
     - uses: actions/checkout@v4
     - uses: actions/setup-java@v4
       with:
         distribution: 'temurin'
         java-version: '17'
     - uses: subosito/flutter-action@v2
       with:
-        channel: 'stable' # or: 'dev' or 'beta'
+        channel: 'stable'
+        cache: true
     - run: dart pub get
     - run: dart format --output=none --set-exit-if-changed .
     - run: dart analyze
@@ -35,5 +37,5 @@ jobs:
       working-directory: example/
     - uses: actions/upload-artifact@v4
       with:
-        name: example-apk-debug
-        path: example/build/app/outputs/apk/debug/app-debug.apk
+        name: example-apk-${{ matrix.variant }}
+        path: example/${{ matrix.artifact-path }}