Fix AttributeError: remove redundant mapping_learned connection in main.py

TopBarWidget already connects mapping_learned to _on_mapping_learned internally
in set_midi_engine, so the external connection in main.py was both redundant
and referenced a non-existent method.

icons.py

@@ -279,6 +279,72 @@ def icon_solo(color: str = "#ffaa00") -> QIcon:
     return _make_icon(paint, color)
 
 
+def icon_cog(color: str = "#aaaaaa") -> QIcon:
+    def paint(p, r, c):
+        pen = QPen(c, r.width() * 0.1)
+        pen.setCapStyle(Qt.RoundCap)
+        p.setPen(pen)
+        p.setBrush(Qt.NoBrush)
+        # Outer circle (gear ring)
+        cx, cy = r.center().x(), r.center().y()
+        outer_r = min(r.width(), r.height()) * 0.42
+        inner_r = outer_r * 0.6
+        # Draw gear teeth (6 bumps)
+        import math
+        p.setBrush(QColor(c))
+        for i in range(6):
+            angle = i * 60 - 30
+            a_rad = math.radians(angle)
+            bx = cx + outer_r * math.cos(a_rad)
+            by = cy + outer_r * math.sin(a_rad)
+            tooth = QPainterPath()
+            tw = r.width() * 0.12
+            th = r.width() * 0.18
+            tooth.addRect(bx - tw/2, by - th/2, tw, th)
+            p.drawRect(bx - tw/2, by - th/2, tw, th)
+        # Center circle
+        p.setPen(Qt.NoPen)
+        p.setBrush(QColor(c))
+        p.drawEllipse(QPointF(cx, cy), inner_r, inner_r)
+        # Inner hole
+        p.setBrush(QColor("#000000"))
+        p.drawEllipse(QPointF(cx, cy), inner_r * 0.55, inner_r * 0.55)
+    return _make_icon(paint, color)
+
+
+def icon_cog(color: str = "#aaaaaa") -> QIcon:
+    def paint(p, r, c):
+        pen = QPen(c, r.width() * 0.1)
+        pen.setCapStyle(Qt.RoundCap)
+        p.setPen(pen)
+        p.setBrush(Qt.NoBrush)
+        # Outer circle (gear ring)
+        cx, cy = r.center().x(), r.center().y()
+        outer_r = min(r.width(), r.height()) * 0.42
+        inner_r = outer_r * 0.6
+        # Draw gear teeth (6 bumps)
+        import math
+        p.setBrush(QColor(c))
+        for i in range(6):
+            angle = i * 60 - 30
+            a_rad = math.radians(angle)
+            bx = cx + outer_r * math.cos(a_rad)
+            by = cy + outer_r * math.sin(a_rad)
+            tooth = QPainterPath()
+            tw = r.width() * 0.12
+            th = r.width() * 0.18
+            tooth.addRect(bx - tw/2, by - th/2, tw, th)
+            p.drawRect(bx - tw/2, by - th/2, tw, th)
+        # Center circle
+        p.setPen(Qt.NoPen)
+        p.setBrush(QColor(c))
+        p.drawEllipse(QPointF(cx, cy), inner_r, inner_r)
+        # Inner hole
+        p.setBrush(QColor("#000000"))
+        p.drawEllipse(QPointF(cx, cy), inner_r * 0.55, inner_r * 0.55)
+    return _make_icon(paint, color)
+
+
 def icon_theme(color: str = "#00ff41") -> QIcon:
     def paint(p, r, c):
         p.setPen(Qt.NoPen)