Fix: Signal date tracking and indicator real-time updates

Issue 1: Only update lastSignalDate when signal type changes (BUY→SELL or SELL→BUY)
- Modified clearIndicatorCaches() to accept clearSignalState parameter
- When new candle completes: only clear cachedResults/cachedMeta (not signal state)
- When timeframe changes: clear everything including signal tracking
- This preserves signal change history across multiple candles

Issue 2: Indicator lines not updating when new candles arrive
- Added updateIndicatorCandles() function to update existing series
- Instead of removing and recreating series, now uses .setData() to update
- Called when new candle is detected to update indicator lines
- Chart renders correctly with new data after each candle completion

Both issues now resolved:
1. Shows last crossover date only when signal actually changes
2. Indicator lines update in real-time when new candles complete

src/api/dashboard/static/js/ui/indicators-panel-new.js

@@ -813,6 +813,61 @@ function renderIndicatorOnPane(indicator, meta, instance, candles, paneIndex, li
     });
 }
 
+// Update existing indicator series with new data (for real-time updates)
+export function updateIndicatorCandles() {
+    if (!window.dashboard || !window.dashboard.chart) return;
+    
+    const activeIndicators = getActiveIndicators();
+    const currentInterval = window.dashboard.currentInterval;
+    const candles = window.dashboard?.allData?.get(currentInterval);
+    
+    if (!candles || candles.length === 0) return;
+    
+    activeIndicators.forEach(indicator => {
+        if (!indicator.visible || indicator.series.length === 0) return;
+        
+        const IndicatorClass = IndicatorRegistry[indicator.type];
+        if (!IndicatorClass) return;
+        
+        const instance = new IndicatorClass(indicator);
+        const results = instance.calculate(candles);
+        
+        if (!results || results.length === 0) return;
+        
+        const meta = instance.getMetadata();
+        
+        // Update each plot series
+        meta.plots.forEach((plot, plotIdx) => {
+            const series = indicator.series[plotIdx];
+            if (!series) return;
+            
+            const plotColor = indicator.params[`_color_${plotIdx}`] || plot.color || '#2962ff';
+            const lineWidth = indicator.params._lineWidth || 2;
+            
+            // Build complete data array
+            const data = [];
+            
+            for (let i = 0; i < candles.length; i++) {
+                const value = results[i]?.[plot.id];
+                if (value !== null && value !== undefined) {
+                    data.push({
+                        time: candles[i].time,
+                        value: value,
+                        color: plotColor,
+                        lineWidth: lineWidth
+                    });
+                }
+            }
+            
+            if (data.length > 0) {
+                series.setData(data);
+            }
+        });
+    });
+    
+    console.log(`[UpdateIndicators] Updated ${activeIndicators.length} indicator series`);
+}
+
 // Chart drawing
 export function drawIndicatorsOnChart() {
     if (!window.dashboard || !window.dashboard.chart) {