Add display refresh rate detection and display

- Added get_monitor_refresh_rates() function in monitor_names.py using Windows ctypes/DEVMODE to detect monitor refresh rates
- Updated DisplayInfo dataclass and Pydantic schema to include refresh_rate field (in Hz)
- Modified get_available_displays() to detect and include refresh rates (defaults to 60Hz on non-Windows or if detection fails)
- Added refresh rate display in Web UI between Resolution and Position
- Added translations for refresh rate label (displays.refresh_rate) in English and Russian locales
- Cross-platform compatible: gracefully falls back to 60Hz default on non-Windows systems

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

server/src/wled_controller/static/locales/en.json

@@ -26,6 +26,7 @@
   "displays.badge.primary": "Primary",
   "displays.badge.secondary": "Secondary",
   "displays.resolution": "Resolution:",
+  "displays.refresh_rate": "Refresh Rate:",
   "displays.position": "Position:",
   "displays.index": "Display Index:",
   "displays.loading": "Loading displays...",