Implement Strategy tab with Ping-Pong backtesting and crossover-based signal logic

- Add 'Strategy' tab to sidebar for backtesting simulations
- Create strategy-panel.js for Ping-Pong and Accumulation mode simulations
- Refactor all indicators (MA, HTS, RSI, MACD, BB, STOCH, Hurst) to use strict crossover-based signal calculation
- Update chart.js with setSimulationMarkers and clearSimulationMarkers support
- Implement single-entry rule in Ping-Pong simulation mode

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

@@ -50,32 +50,37 @@ function calculateEMAInline(data, period) {
 }
 
 // Signal calculation for MACD
-function calculateMACDSignal(indicator, lastCandle, prevCandle, values) {
+function calculateMACDSignal(indicator, lastCandle, prevCandle, values, prevValues) {
     const macd = values?.macd;
     const signal = values?.signal;
-    const histogram = values?.histogram;
+    const prevMacd = prevValues?.macd;
+    const prevSignal = prevValues?.signal;
     
-    if (!macd || macd === null || !signal || signal === null) {
+    if (macd === undefined || macd === null || signal === undefined || signal === null || 
+        prevMacd === undefined || prevMacd === null || prevSignal === undefined || prevSignal === null) {
         return null;
     }
 
-    let signalType, strength, reasoning;
-
-    const prevCandleHistogram = prevCandle ? values?.histogram : null;
-
-    if (macd > signal) {
-        signalType = SIGNAL_TYPES.BUY;
-        strength = Math.min(50 + histogram * 500, 100);
-        reasoning = `MACD (${macd.toFixed(2)}) is above Signal (${signal.toFixed(2)})`;
-    } else if (macd < signal) {
-        signalType = SIGNAL_TYPES.SELL;
-        strength = Math.min(50 + Math.abs(histogram) * 500, 100);
-        reasoning = `MACD (${macd.toFixed(2)}) is below Signal (${signal.toFixed(2)})`;
-    } else {
-        return null;
+    // BUY: MACD crosses UP through Signal line
+    if (prevMacd <= prevSignal && macd > signal) {
+        return {
+            type: SIGNAL_TYPES.BUY,
+            strength: 80,
+            value: macd,
+            reasoning: `MACD crossed UP through Signal line`
+        };
+    } 
+    // SELL: MACD crosses DOWN through Signal line
+    else if (prevMacd >= prevSignal && macd < signal) {
+        return {
+            type: SIGNAL_TYPES.SELL,
+            strength: 80,
+            value: macd,
+            reasoning: `MACD crossed DOWN through Signal line`
+        };
     }
 
-    return { type: signalType, strength, value: macd, reasoning };
+    return null;
 }
 
 // MACD Indicator class