Add external configuration file system

Breaking Changes:
- Configuration now via config.json instead of editing Python code
- Remove all hardcoded paths (no more /home/berwn)
- Separate system config (config.json) from runtime config (user_config.json)

Features:
- config.example.json with all configurable options
- GPIO pin and state configuration
- Audio device index configuration
- Customizable paths (relative or absolute)
- Web port and upload size settings
- No code editing required for deployment

Configuration Structure:
- gpio: hook_pin, hook_pressed_state
- audio: device_index, chunk_size, channels, sample_rate, max_record_seconds
- paths: base_dir, recordings_dir, sounds_dir
- web: port, max_upload_size_mb
- system: active_greeting, default_volume

Script automatically:
- Checks for config.json on startup
- Provides helpful error if missing
- Uses relative paths by default
- Loads test_complete.py config from same file

Updated Documentation:
- Complete configuration guide in README
- Setup instructions without hardcoded paths
- Troubleshooting for config errors
- Device index discovery command

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

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

.gitignore

@@ -44,6 +44,7 @@ sounds/
 
 # Configuration
 config.json
+user_config.json
 *.backup
 
 # Logs