Add Android app with Google Calendar year view and OAuth integration

.github/workflows/android-build.yml

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+name: Android CI - Build APK
+
+on:
+  push:
+    branches: [ claude/android-calendar-year-view-Ckk5P ]
+    paths:
+      - 'YearCalendar/**'
+  pull_request:
+    branches: [ main ]
+    paths:
+      - 'YearCalendar/**'
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: YearCalendar
+
+    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: Create local.properties with OAuth credentials
+      run: |
+        echo "google.client.id=${{ secrets.GOOGLE_CLIENT_ID }}" > local.properties
+        echo "google.client.secret=${{ secrets.GOOGLE_CLIENT_SECRET }}" >> local.properties
+        echo "google.project.id=${{ secrets.GOOGLE_PROJECT_ID }}" >> local.properties
+
+    - name: Build Debug APK
+      run: ./gradlew assembleDebug --stacktrace
+
+    - name: Upload Debug APK
+      uses: actions/upload-artifact@v4
+      with:
+        name: year-calendar-debug-apk
+        path: YearCalendar/app/build/outputs/apk/debug/app-debug.apk
+        retention-days: 30
+
+    - name: Build Release APK (unsigned)
+      run: ./gradlew assembleRelease --stacktrace
+      continue-on-error: true
+
+    - name: Upload Release APK
+      uses: actions/upload-artifact@v4
+      if: success()
+      with:
+        name: year-calendar-release-apk
+        path: YearCalendar/app/build/outputs/apk/release/app-release-unsigned.apk
+        retention-days: 30
+
+    - name: Display APK info
+      if: success()
+      run: |
+        echo "✅ APK build successful!"
+        echo "📦 Debug APK: YearCalendar/app/build/outputs/apk/debug/app-debug.apk"
+        ls -lh app/build/outputs/apk/debug/ || true

YearCalendar/.gitignore

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+*.iml
+.gradle
+/local.properties
+/.idea/caches
+/.idea/libraries
+/.idea/modules.xml
+/.idea/workspace.xml
+/.idea/navEditor.xml
+/.idea/assetWizardSettings.xml
+.DS_Store
+/build
+/captures
+.externalNativeBuild
+.cxx
+local.properties
+
+# Sensitive files - DO NOT COMMIT
+local.properties
+app/google-services.json
+*.keystore
+*.jks

YearCalendar/CI_SETUP.md

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+# CI/CD Setup for Year Calendar
+
+This project uses GitHub Actions to automatically build APKs on every push.
+
+## GitHub Secrets Configuration
+
+To enable automatic APK builds, you need to add your OAuth credentials as GitHub repository secrets.
+
+### Step 1: Navigate to Repository Settings
+
+1. Go to your GitHub repository: `https://github.com/blooop/scratch_env`
+2. Click **Settings** tab
+3. In the left sidebar, click **Secrets and variables** → **Actions**
+4. Click **New repository secret**
+
+### Step 2: Add Required Secrets
+
+Add these three secrets:
+
+#### Secret 1: GOOGLE_CLIENT_ID
+- Name: `GOOGLE_CLIENT_ID`
+- Value: Your Google OAuth Client ID (format: `xxx-xxx.apps.googleusercontent.com`)
+
+#### Secret 2: GOOGLE_CLIENT_SECRET
+- Name: `GOOGLE_CLIENT_SECRET`
+- Value: Your Google OAuth Client Secret (format: `GOCSPX-xxxxx`)
+
+#### Secret 3: GOOGLE_PROJECT_ID
+- Name: `GOOGLE_PROJECT_ID`
+- Value: Your Google Cloud Project ID
+
+**Note:** Use the OAuth credentials that were provided to you separately.
+
+### Step 3: Verify Secrets
+
+After adding all three secrets, you should see:
+- ✅ GOOGLE_CLIENT_ID
+- ✅ GOOGLE_CLIENT_SECRET
+- ✅ GOOGLE_PROJECT_ID
+
+## How CI/CD Works
+
+### Automatic Builds
+
+The workflow automatically triggers on:
+- **Push** to branch `claude/android-calendar-year-view-Ckk5P`
+- **Pull requests** to `main` branch
+- **Manual trigger** via GitHub Actions UI
+
+### Build Process
+
+1. Checks out code
+2. Sets up Java 17
+3. Injects OAuth credentials from secrets into `local.properties`
+4. Builds debug APK
+5. Builds release APK (unsigned)
+6. Uploads APKs as artifacts
+
+### Build Artifacts
+
+After a successful build, you can download the APKs:
+
+1. Go to the **Actions** tab in your repository
+2. Click on the latest workflow run
+3. Scroll down to **Artifacts** section
+4. Download:
+   - `year-calendar-debug-apk` - Ready to install on any device
+   - `year-calendar-release-apk` - Optimized but unsigned
+
+## Downloading Your APK
+
+### Method 1: From GitHub Actions UI
+
+1. Navigate to: `https://github.com/blooop/scratch_env/actions`
+2. Click on the most recent **"Android CI - Build APK"** workflow run
+3. Scroll to bottom → **Artifacts** section
+4. Click **year-calendar-debug-apk** to download
+5. Extract the ZIP file
+6. Transfer `app-debug.apk` to your Android device
+
+### Method 2: Using GitHub CLI
+
+```bash
+# List recent workflow runs
+gh run list --workflow=android-build.yml
+
+# Download artifacts from latest run
+gh run download --name year-calendar-debug-apk
+```
+
+## Installing APK on Android Device
+
+### Enable Installation from Unknown Sources
+
+1. On your Android device, go to **Settings**
+2. Navigate to **Security** (or **Apps & notifications** → **Special app access**)
+3. Enable **Install unknown apps** for your file manager or browser
+
+### Install the APK
+
+#### Method A: Direct Download
+1. Open the downloaded ZIP on your Android device
+2. Extract `app-debug.apk`
+3. Tap the APK file
+4. Tap **Install**
+5. Tap **Open** when installation completes
+
+#### Method B: ADB Install
+```bash
+# Connect device via USB with USB debugging enabled
+adb install app-debug.apk
+```
+
+#### Method C: Wireless Transfer
+1. Upload APK to Google Drive or similar
+2. Download on Android device
+3. Open and install
+
+## Manual Build (Alternative)
+
+If you need to build locally:
+
+```bash
+cd YearCalendar
+
+# Create local.properties with credentials
+echo "google.client.id=YOUR_CLIENT_ID" > local.properties
+echo "google.client.secret=YOUR_SECRET" >> local.properties
+echo "google.project.id=YOUR_PROJECT_ID" >> local.properties
+
+# Build debug APK
+./gradlew assembleDebug
+
+# APK location
+ls -lh app/build/outputs/apk/debug/app-debug.apk
+```
+
+## Workflow File Location
+
+The CI/CD configuration is located at:
+```
+.github/workflows/android-build.yml
+```
+
+## Troubleshooting
+
+### Build Fails with "Secrets not found"
+
+**Solution:** Ensure all three secrets are added to GitHub repository settings.
+
+### Build Fails with Gradle Errors
+
+**Solution:** Check the workflow logs in the Actions tab for detailed error messages.
+
+### APK Not Generated
+
+**Solution:**
+1. Check if the workflow ran successfully (green checkmark)
+2. Verify the YearCalendar directory has changes
+3. Look at workflow logs for errors
+
+### APK Won't Install on Device
+
+**Symptoms:** "App not installed" or "Package conflicts"
+
+**Solutions:**
+- Uninstall any previous version first
+- Enable installation from unknown sources
+- Check Android version is 8.0 (API 26) or higher
+- Verify APK file isn't corrupted (re-download if needed)
+
+### SHA-1 Fingerprint Issues
+
+The debug APK is signed with Android's default debug keystore. The SHA-1 is:
+```
+Keystore: ~/.android/debug.keystore
+Alias: androiddebugkey
+Password: android
+```
+
+To get the SHA-1:
+```bash
+keytool -list -v -keystore ~/.android/debug.keystore \
+  -alias androiddebugkey -storepass android -keypass android
+```
+
+**Important:** For the APK to work with Google OAuth, you need to add this SHA-1 to your Google Cloud Console OAuth credentials.
+
+## Production Release
+
+For a production-signed APK:
+
+1. Generate a release keystore:
+   ```bash
+   keytool -genkey -v -keystore release.keystore \
+     -alias year-calendar -keyalg RSA -keysize 2048 -validity 10000
+   ```
+
+2. Add keystore secrets to GitHub:
+   - `RELEASE_KEYSTORE` (base64 encoded keystore file)
+   - `RELEASE_KEYSTORE_PASSWORD`
+   - `RELEASE_KEY_ALIAS`
+   - `RELEASE_KEY_PASSWORD`
+
+3. Update workflow to sign release builds
+
+4. Register release SHA-1 in Google Cloud Console
+
+## Security Notes
+
+✅ **Secure:**
+- Secrets are encrypted in GitHub
+- Not exposed in logs
+- Only accessible during workflow runs
+- Automatically injected into build
+
+⚠️ **Best Practices:**
+- Rotate secrets periodically
+- Use different credentials for production
+- Never commit secrets to repository
+- Review workflow runs for unauthorized access
+
+## Build Status
+
+Check the current build status:
+
+[![Android CI](https://github.com/blooop/scratch_env/actions/workflows/android-build.yml/badge.svg)](https://github.com/blooop/scratch_env/actions/workflows/android-build.yml)
+
+## Additional Resources
+
+- [GitHub Actions Documentation](https://docs.github.com/en/actions)
+- [Android CI Best Practices](https://developer.android.com/studio/build)
+- [APK Installation Guide](https://www.androidauthority.com/how-to-install-apks-31494/)
+
+## Support
+
+If you encounter issues:
+1. Check workflow logs in Actions tab
+2. Review error messages
+3. Verify secrets are configured correctly
+4. Ensure device meets minimum requirements (Android 8.0+)