feat: restyle chart v2 colors, end labels and legend

- CTF line: black instead of red
- WorstOf line: red + end label shows "Name (value)" format
- Other underlyings: vivid palette (teal/amber/purple/sky/indigo/orange) instead of grey shades; end label shows name
- Barriera Capitale: brown to avoid confusion with WorstOf red
- PrezzoWorst dashed line: red aligned with WorstOf
- Legend font increased 10→12px
- Legend entry for WorstOf shows "Name (Worst Of)"

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

CertReports.Syncfusion/Services/Implementations/SkiaChartRendererV2.cs

@@ -16,21 +16,23 @@ namespace CertReports.Syncfusion.Services.Implementations;
 public static class SkiaChartRendererV2
 {
     // ── Colori ────────────────────────────────────────────────────────
-    private static readonly SKColor CertColor        = new(204, 0, 0);
-    private static readonly SKColor WorstOfColor     = new(21, 101, 192);
+    private static readonly SKColor CertColor        = new(0, 0, 0);          // nero
+    private static readonly SKColor WorstOfColor     = new(204, 0, 0);        // rosso
     private static readonly SKColor StrikeColor      = new(46, 125, 50);
-    private static readonly SKColor CapitaleColor    = new(204, 0, 0);
+    private static readonly SKColor CapitaleColor    = new(121, 85, 72);      // marrone
     private static readonly SKColor CouponColor      = new(128, 0, 128);
     private static readonly SKColor AutocallColor    = new(230, 81, 0);
-    private static readonly SKColor PrezzoWorstColor = new(21, 101, 192);
+    private static readonly SKColor PrezzoWorstColor = new(204, 0, 0);        // rosso (allineato WorstOf)
     private static readonly SKColor TitleColor       = new(21, 101, 192);
 
     private static readonly SKColor[] OtherUlColors =
     {
-        new(120, 120, 120),
-        new(160, 160, 160),
-        new(90,  90,  90),
-        new(140, 140, 140),
+        new(0,   150, 136),  // teal
+        new(255, 152,   0),  // amber
+        new(156,  39, 176),  // viola
+        new(  3, 169, 244),  // celeste
+        new( 63,  81, 181),  // indigo
+        new(255,  87,  34),  // arancio scuro
     };
 
     // ── Font helper ───────────────────────────────────────────────────
@@ -138,19 +140,26 @@ public static class SkiaChartRendererV2
 
             SKColor color;
             float thickness;
+            string seriesLabel;
+            string endLabel;
             if (ul.IsWorstOf == 1)
             {
                 color = WorstOfColor;
                 thickness = 2f;
+                seriesLabel = $"{ul.Sottostante} (Worst Of)";
+                endLabel = $"{ul.Sottostante} ({ul.PriceWorst:0.00})";
             }
             else
             {
                 color = OtherUlColors[otherColorIdx++ % OtherUlColors.Length];
                 thickness = 1f;
+                seriesLabel = ul.Sottostante;
+                endLabel = ul.Sottostante;
             }
 
             DrawSeriesV2(canvas, plotArea, ulPoints, minDate, maxDate, minY, maxY, color, thickness);
-            seriesLegend.Add((ul.Sottostante, color, false, thickness));
+            DrawSeriesEndLabel(canvas, plotArea, ulPoints, minDate, maxDate, minY, maxY, color, endLabel);
+            seriesLegend.Add((seriesLabel, color, false, thickness));
         }
 
         // Bordo area plot
@@ -358,6 +367,25 @@ public static class SkiaChartRendererV2
         canvas.Restore();
     }
 
+    // ═══════════════════════════════════════════════════════════════════
+    // Label al termine di una serie (estremo destro)
+    // ═══════════════════════════════════════════════════════════════════
+
+    private static void DrawSeriesEndLabel(SKCanvas canvas, SKRect area,
+        List<ChartSeriesPoint> points,
+        DateTime minDate, DateTime maxDate, double minY, double maxY,
+        SKColor color, string label)
+    {
+        if (points.Count == 0) return;
+        var last = points.Last();
+        float y = ValueToY((double)last.Performance, area, minY, maxY);
+        y = Math.Max(area.Top, Math.Min(area.Bottom, y));
+
+        var font = CreateFont(9.5f);
+        using var textPaint = new SKPaint { Color = color, IsAntialias = true };
+        canvas.DrawText(label, area.Right + 5, y + 4, SKTextAlign.Left, font, textPaint);
+    }
+
     // ═══════════════════════════════════════════════════════════════════
     // Linea orizzontale costante con label a destra
     // ═══════════════════════════════════════════════════════════════════
@@ -400,7 +428,7 @@ public static class SkiaChartRendererV2
         const float itemGap = 14;
         const float rowHeight = 19;
 
-        var font = CreateFont(10f);
+        var font = CreateFont(12f);
 
         foreach (var (name, color, dashed, thickness) in items)
         {