feat: add Tailscale auto-update and Ethernet network settings

[toneyche]

Summary

This PR adds two new features and fixes a bug:

New Features

1. Tailscale Auto-Update Toggle

   • Add auto-update switch in Tailscale settings page
   • Users can enable/disable automatic Tailscale updates

2. Ethernet Network Configuration

   • Add network settings page under Device settings
   • Support DHCP and Static IP configuration
   • Allow setting static IP address, netmask, gateway, and DNS servers

Bug Fixes

• Fix Tailscale auto-update preference parsing: The previous implementation checked for a compact JSON string, but tailscale debug prefs outputs formatted multi-line JSON. Updated to properly parse the JSON structure.

Changes

Backend (server/)

• proto/tailscale.go: Add SetAutoUpdateReq struct
• proto/network.go: Add Ethernet configuration structs
• router/extensions.go: Add auto-update API routes
• router/network.go: Add Ethernet API routes
• service/extensions/tailscale/: Implement auto-update get/set functions
• service/network/ethernet.go: Implement Ethernet configuration service

Frontend (web/)

• api/extensions/tailscale.ts: Add auto-update API calls
• api/network.ts: Add Ethernet API calls
• pages/desktop/menu/settings/tailscale/device.tsx: Add auto-update switch
• pages/desktop/menu/settings/device/ethernet.tsx: New Ethernet settings component
• pages/desktop/menu/settings/device/index.tsx: Add Ethernet settings entry
• i18n/locales/en.ts & zh.ts: Add translations

Test Plan

• Test Tailscale auto-update toggle saves and persists correctly
• Test Ethernet DHCP mode
• Test Ethernet Static IP configuration
• Verify settings are preserved after page refresh