feat: optimize system monitor with async I/O and traffic since reboot

- Replace synchronous file operations with async aiofiles
- Implement concurrent data gathering using asyncio.gather()
- Move API calls to thread pool executor
- Add LRU cache for config file reads
- Optimize parsing functions for single-pass processing
- Reduce measurement intervals for faster response times
- Add system uptime and boot time display
- Track total network traffic since last reboot from /proc/net/dev
- Separate system traffic (since reboot) from user traffic (all-time)
- Add human-readable uptime formatting
- Enhance output with clear traffic categorization

requirements.txt

@@ -22,6 +22,7 @@ urllib3==2.5.0
 yarl==1.20.1
 hysteria2-api==0.1.3
 schedule==1.2.2
+aiofiles==24.1.0
 
 # webpanel
 annotated-types==0.7.0