feat: add Echo Chamber Android app for friend reviews

Implements a Kivy-based Android app that allows users to collect and view reviews from friends. The app includes:

- Review feed displaying all friend reviews
- Form to add new reviews with friend name, topic, and review text
- Friend management screen to add/remove friends
- Local JSON-based data storage
- Comprehensive test suite with 11 tests

Technical details:
- Built with Kivy framework for cross-platform compatibility
- Buildozer.spec configured for Android APK generation
- Automatic friend addition when creating reviews
- Persistent storage using JSON files
- All tests passing

The app can be run on desktop for testing or built as an Android APK using buildozer.

Author: claude

echo_chamber/README.md

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+# Echo Chamber
+
+An Android app for collecting and viewing reviews from your friends!
+
+## Features
+
+- **Review Feed**: View all reviews from your friends in one place
+- **Add Reviews**: Record reviews from friends on various topics
+- **Friend Management**: Add and manage your friend list
+- **Local Storage**: All data stored locally on your device
+
+## How It Works
+
+1. **Add Friends**: Navigate to the Friends screen and add your friends
+2. **Create Reviews**: Tap "New Review" to record feedback from a friend
+3. **View Feed**: See all reviews on the home screen
+
+## Running the App
+
+### Desktop (for testing)
+
+Install dependencies:
+```bash
+pixi add kivy
+pixi run python echo_chamber/main.py
+```
+
+Or with pip:
+```bash
+pip install kivy
+python echo_chamber/main.py
+```
+
+### Building for Android
+
+1. Install Buildozer:
+   ```bash
+   pip install buildozer
+   ```
+
+2. Install Android build dependencies (Ubuntu/Debian):
+   ```bash
+   sudo apt update
+   sudo apt install -y git zip unzip openjdk-17-jdk python3-pip autoconf libtool pkg-config zlib1g-dev libncurses5-dev libncursesw5-dev libtinfo5 cmake libffi-dev libssl-dev
+   ```
+
+3. Build the APK:
+   ```bash
+   buildozer android debug
+   ```
+
+4. The APK will be generated in `bin/` directory
+
+5. Install on device:
+   ```bash
+   buildozer android deploy run
+   ```
+
+## Project Structure
+
+```
+echo_chamber/
+├── __init__.py       # Package initialization
+├── main.py           # Main app with UI screens
+├── storage.py        # Data storage handling
+└── README.md         # This file
+```
+
+## Data Storage
+
+Reviews and friends are stored as JSON files:
+- `reviews.json`: All review entries
+- `friends.json`: Friend list
+
+By default, data is stored in the current directory. On Android, it will be in the app's private storage.
+
+## Development
+
+The app uses Kivy framework for cross-platform UI. Key screens:
+- `HomeScreen`: Main feed displaying all reviews
+- `NewReviewScreen`: Form to add new reviews
+- `FriendsScreen`: Manage friend list
+
+## Future Enhancements
+
+Potential features to add:
+- Cloud sync between devices
+- Share reviews with friends
+- Review categories/tags
+- Search and filter reviews
+- Profile pictures for friends
+- Rating system (stars, thumbs up/down)
+- Comments on reviews
+- Export reviews to PDF/text

echo_chamber/__init__.py

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+"""Echo Chamber - Get reviews from your friends."""
+
+__version__ = "0.1.0"