Add v0.9.5 features: minimize to tray, settings, relay support

## New Features

### Minimize to Tray
- Window minimizes to system tray instead of taskbar
- Tray notification shown when minimized
- Double-click tray icon to restore

### Settings System
- New settings dialog (Edit > Settings or Ctrl+,)
- JSON-based settings persistence
- General tab: minimize to tray toggle
- Relay Server tab: enable/configure relay connection

### Relay Server Support
- New relay_client.py for connecting to relay server
- WebSocket client with auto-reconnection
- Forwards API requests to local server
- Updates QR code/URL when relay connected

### PWA Updates
- Added relay mode detection and authentication
- Password passed via header for API requests
- WebSocket authentication for relay connections
- Desktop status handling (connected/disconnected)
- Wake lock icon now always visible with status indicator

## Files Added
- gui/settings_manager.py
- gui/settings_dialog.py
- relay_client.py

## Dependencies
- Added aiohttp>=3.9.0 for relay client

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

config.py

@@ -1,7 +1,8 @@
 # Configuration and constants for MacroPad Server
 
-VERSION = "0.9.3"
+VERSION = "0.9.5"
 DEFAULT_PORT = 40000
+SETTINGS_FILE = "settings.json"
 
 # UI Theme colors
 THEME = {