Add production WSGI server and CLAUDE.md documentation

- Replace Flask development server with Waitress production WSGI server
- Add waitress>=2.1.0 dependency to pyproject.toml and Makefile
- Configure 4-thread server for better performance and stability
- Create comprehensive CLAUDE.md guide for future development
- Document architecture, deployment, testing, and common patterns
- Update README.md with production-ready feature and dependencies

Eliminates Flask development server warning and provides production-grade
web serving suitable for Raspberry Pi deployment.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

README.md

@@ -73,6 +73,7 @@ Web interface available at: `http://<raspberry-pi-ip>:8080`
 - **USB Backup**: Automatic backup to multiple USB drives with CRC32 verification
 - **Data Integrity**: Every file write is verified with CRC checksums
 - **HiFiBerry Support**: Optimized for HiFiBerry DAC+ADC Pro audio quality
+- **Production-Ready**: Uses Waitress WSGI server for stable, production-grade web serving
 - **Real-time Status**: Monitor phone status (on-hook/off-hook/recording)
 - **Auto-refresh**: Status updates every 5 seconds
 
@@ -95,6 +96,7 @@ Web interface available at: `http://<raspberry-pi-ip>:8080`
   - numpy>=1.21.0
   - pyaudio>=0.2.13
   - RPi.GPIO>=0.7.1
+  - waitress>=2.1.0 (production WSGI server)
 
 ## Installation
 
@@ -127,7 +129,7 @@ sudo apt-get install -y python3-pyaudio portaudio19-dev
 # Install Python dependencies with UV
 make sync
 # Or manually:
-# uv pip install flask numpy pyaudio RPi.GPIO
+# uv pip install flask numpy pyaudio RPi.GPIO waitress
 ```
 
 #### Option B: Using pip
@@ -135,7 +137,7 @@ make sync
 ```bash
 sudo apt-get update
 sudo apt-get install -y python3-pip python3-pyaudio portaudio19-dev
-pip3 install flask numpy RPi.GPIO
+pip3 install flask numpy RPi.GPIO waitress
 ```
 
 ### 4. Configure HiFiBerry