Add configurable RSI levels and remove line settings for RSI

RSI Changes:
- Add overbought and oversold level inputs (default 70/30)
- Update calculate() to return overboughtBand and oversoldBand instead of hardcoded bands
- Update plots to use overboughtBand and oversoldBand with fixed style='dashed' and width=1
- This makes RSI bands adjustable while keeping line style and width fixed

Configuration Panel:
- Hide Line Type and Line Width settings for RSI (indicator.type === 'rsi')
- RSI bands always dashed at 1px width as standard
- Overbought and oversold levels now appear as configurable parameters

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

@@ -281,6 +281,7 @@ return `
                     `.trim() + '';
                 }).join('')}
                 
+                ${indicator.type !== 'rsi' ? `
                 <div class="config-row">
                     <label>Line Type</label>
                     <select onchange="window.updateIndicatorSetting && window.updateIndicatorSetting('${indicator.id}', '_lineType', this.value)">
@@ -293,6 +294,7 @@ return `
                     <input type="range" min="1" max="5" value="${indicator.params._lineWidth || 2}" onchange="this.nextElementSibling.textContent = this.value; window.updateIndicatorSetting && window.updateIndicatorSetting('${indicator.id}', '_lineWidth', parseInt(this.value))">
                     <span class="range-value">${indicator.params._lineWidth || 2}</span>
                 </div>
+                ` : ''}
             </div>
             
             ${meta?.inputs && meta.inputs.length > 0 ? `