Add GitHub Actions workflow for APK build and release

- Build debug and release APKs on push to main
- Upload APKs as artifacts on every build
- Create GitHub release with APKs when tagged with v*

Generated with [Claude Code](https://claude.ai/code)
via [Happy](https://happy.engineering)

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

Author: 3 people

.github/workflows/build.yml

@@ -0,0 +1,94 @@
+name: Build & Release APK
+
+on:
+  push:
+    branches: [main]
+    tags:
+      - 'v*'
+  pull_request:
+    branches: [main]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        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: Build Debug APK
+        run: ./gradlew assembleDebug
+
+      - name: Build Release APK
+        run: ./gradlew assembleRelease
+
+      - name: Upload Debug APK
+        uses: actions/upload-artifact@v4
+        with:
+          name: oo-chat-debug
+          path: app/build/outputs/apk/debug/app-debug.apk
+
+      - name: Upload Release APK
+        uses: actions/upload-artifact@v4
+        with:
+          name: oo-chat-release
+          path: app/build/outputs/apk/release/app-release-unsigned.apk
+
+  release:
+    needs: build
+    runs-on: ubuntu-latest
+    if: startsWith(github.ref, 'refs/tags/v')
+
+    steps:
+      - name: Download Release APK
+        uses: actions/download-artifact@v4
+        with:
+          name: oo-chat-release
+
+      - name: Download Debug APK
+        uses: actions/download-artifact@v4
+        with:
+          name: oo-chat-debug
+
+      - name: Get version from tag
+        id: get_version
+        run: echo "VERSION=${GITHUB_REF#refs/tags/v}" >> $GITHUB_OUTPUT
+
+      - name: Rename APKs
+        run: |
+          mv app-release-unsigned.apk oo-chat-${{ steps.get_version.outputs.VERSION }}-release.apk
+          mv app-debug.apk oo-chat-${{ steps.get_version.outputs.VERSION }}-debug.apk
+
+      - name: Create Release
+        uses: softprops/action-gh-release@v1
+        with:
+          name: OO Chat Android v${{ steps.get_version.outputs.VERSION }}
+          body: |
+            ## OO Chat Android v${{ steps.get_version.outputs.VERSION }}
+
+            Native Android chat client for ConnectOnion agents.
+
+            ### Downloads
+            - **oo-chat-${{ steps.get_version.outputs.VERSION }}-debug.apk** - Debug build (recommended for testing)
+            - **oo-chat-${{ steps.get_version.outputs.VERSION }}-release.apk** - Release build (unsigned)
+
+            ### Features
+            - Connect to agents by address (0x...)
+            - Ed25519 signed messages
+            - Real-time streaming (tool calls, thinking, responses)
+            - Multi-turn conversations with session persistence
+          files: |
+            oo-chat-${{ steps.get_version.outputs.VERSION }}-release.apk
+            oo-chat-${{ steps.get_version.outputs.VERSION }}-debug.apk
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}