Fix RSI bands visibility and line width

1. Added band creation:
   - Create horizontal price lines for RSI overbought/oversold bands
   - Use createPriceLine() on the RSI series after it's created
   - Create lines at indicator.params.overbought and indicator.params.oversold levels
   - Store band references to prevent creating duplicate lines

2. Fixed line width priority:
   - Changed from 'indicator.params._lineWidth || plot.width || lineWidth'
   - To 'plot.width || indicator.params._lineWidth || lineWidth'
   - This ensures RSI bands use fixed 1px width from plot.width metadata
   - User can still adjust line width for other indicators

Result: RSI bands now visible as dashed lines at 70/30 levels

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

@@ -697,7 +697,7 @@ function renderIndicatorOnPane(indicator, meta, instance, candles, paneIndex, li
                 topFillColor2: '#00000000',
                 bottomFillColor1: '#00000000',
                 bottomColor: plot.bottomColor || '#00000000',
-                lineWidth: indicator.params._lineWidth || plot.width || lineWidth,
+                lineWidth: plot.width || indicator.params._lineWidth || lineWidth,
                 lineStyle: plotLineStyle,
                 title: plot.title || '',
                 priceLineVisible: false,
@@ -706,7 +706,7 @@ function renderIndicatorOnPane(indicator, meta, instance, candles, paneIndex, li
         } else {
             series = window.dashboard.chart.addSeries(LightweightCharts.LineSeries, {
                 color: plotColor,
-                lineWidth: indicator.params._lineWidth || plot.width || lineWidth,
+                lineWidth: plot.width || indicator.params._lineWidth || lineWidth,
                 lineStyle: plotLineStyle,
                 title: plot.title || '',
                 priceLineVisible: false,
@@ -716,6 +716,41 @@ function renderIndicatorOnPane(indicator, meta, instance, candles, paneIndex, li
         
         series.setData(data);
         indicator.series.push(series);
+        
+        // Create horizontal band lines for RSI
+        if (meta.name === 'RSI' && indicator.series.length > 0) {
+            const mainSeries = indicator.series[0];
+            const overbought = indicator.params.overbought || 70;
+            const oversold = indicator.params.oversold || 30;
+            
+            // Remove existing price lines first
+            while (indicator.bands && indicator.bands.length > 0) {
+                try {
+                    indicator.bands.pop();
+                } catch(e) {}
+            }
+            indicator.bands = indicator.bands || [];
+            
+            // Create overbought band line
+            indicator.bands.push(mainSeries.createPriceLine({
+                price: overbought,
+                color: '#787B86',
+                lineWidth: 1,
+                lineStyle: LightweightCharts.LineStyle.Dashed,
+                axisLabelVisible: false,
+                title: ''
+            }));
+            
+            // Create oversold band line
+            indicator.bands.push(mainSeries.createPriceLine({
+                price: oversold,
+                color: '#787B86',
+                lineWidth: 1,
+                lineStyle: LightweightCharts.LineStyle.Dashed,
+                axisLabelVisible: false,
+                title: ''
+            }));
+        }
     });
 }