Refactor dashboard JS to ES modules; fix collector strategy loading and add auto-backfill

- Split inline JS into separate ES module files (indicators/, strategies/, ui/, utils/)
- Fix brain.py strategy registry to use MAStrategy directly instead of missing modules
- Add auto-backfill for detected data gaps in collector monitoring loop
- Fix chart resize on sidebar toggle
- Fix chart scrollToTime -> setVisibleLogicalRange

src/api/dashboard/static/js/indicators/bb.js

@@ -0,0 +1,41 @@
+import { BaseIndicator } from './base.js';
+
+export class BollingerBandsIndicator extends BaseIndicator {
+    calculate(candles) {
+        const period = this.params.period || 20;
+        const stdDevMult = this.params.stdDev || 2;
+        const results = new Array(candles.length).fill(null);
+        
+        for (let i = period - 1; i < candles.length; i++) {
+            let sum = 0;
+            for (let j = 0; j < period; j++) sum += candles[i-j].close;
+            const sma = sum / period;
+            
+            let diffSum = 0;
+            for (let j = 0; j < period; j++) diffSum += Math.pow(candles[i-j].close - sma, 2);
+            const stdDev = Math.sqrt(diffSum / period);
+            
+            results[i] = {
+                middle: sma,
+                upper: sma + (stdDevMult * stdDev),
+                lower: sma - (stdDevMult * stdDev)
+            };
+        }
+        return results;
+    }
+    
+    getMetadata() {
+        return {
+            name: 'Bollinger Bands',
+            inputs: [
+                { name: 'period', label: 'Period', type: 'number', default: 20, min: 1, max: 100 },
+                { name: 'stdDev', label: 'Std Dev', type: 'number', default: 2, min: 0.5, max: 5, step: 0.5 }
+            ],
+            plots: [
+                { id: 'upper', color: '#4caf50', title: 'Upper' },
+                { id: 'middle', color: '#4caf50', title: 'Middle', lineStyle: 2 },
+                { id: 'lower', color: '#4caf50', title: 'Lower' }
+            ]
+        };
+    }
+}