feat: K线图添加技术指标切换(MA/EMA/BOLL/VOL/MACD)，修复设置面板显示问题

flutter_monisuo/lib/providers/chart_provider.dart

@@ -22,6 +22,7 @@ class IndicatorSettings {
   final bool showEMA;
   final bool showBOLL;
   final bool showVOL;
+  final bool showMACD;
   final int maPeriod;
   final int emaPeriod;
   final int bollPeriod;
@@ -31,6 +32,7 @@ class IndicatorSettings {
     this.showEMA = false,
     this.showBOLL = false,
     this.showVOL = true,
+    this.showMACD = false,
     this.maPeriod = 7,
     this.emaPeriod = 14,
     this.bollPeriod = 20,
@@ -41,6 +43,7 @@ class IndicatorSettings {
     bool? showEMA,
     bool? showBOLL,
     bool? showVOL,
+    bool? showMACD,
     int? maPeriod,
     int? emaPeriod,
     int? bollPeriod,
@@ -50,6 +53,7 @@ class IndicatorSettings {
       showEMA: showEMA ?? this.showEMA,
       showBOLL: showBOLL ?? this.showBOLL,
       showVOL: showVOL ?? this.showVOL,
+      showMACD: showMACD ?? this.showMACD,
       maPeriod: maPeriod ?? this.maPeriod,
       emaPeriod: emaPeriod ?? this.emaPeriod,
       bollPeriod: bollPeriod ?? this.bollPeriod,