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/app.js

@@ -268,6 +268,10 @@ async function loadDisplays() {
                     <span class="info-label">${t('displays.resolution')}</span>
                     <span class="info-value">${display.width} × ${display.height}</span>
                 </div>
+                <div class="info-row">
+                    <span class="info-label">${t('displays.refresh_rate')}</span>
+                    <span class="info-value">${display.refresh_rate}Hz</span>
+                </div>
                 <div class="info-row">
                     <span class="info-label">${t('displays.position')}</span>
                     <span class="info-value">(${display.x}, ${display.y})</span>