Multi-select, context menu, section strikethrough, rename/duplicate presets

- Multi-select strips with click, Ctrl+click (toggle), Shift+click (range, same zone)
- Right-click selected strip: context menu with Cascade CC, Assign Channel, Deselect All
- Right-click unselected strip: clears all selections
- Selection status label shows count and type (faders/toggles/transport toggles)
- Rename preset button added to preset row
- Duplicate preset button auto-generates new UUID
- Layout panel section buttons show strikethrough when hidden, normal when visible
- Renamed Preset Browser to Instrument Browser in UI
- Transport strips wired for multi-select and context menu

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

togglewidget.py

@@ -200,21 +200,32 @@ class ToggleWidget(QWidget):
 
         outer.addWidget(self.container)
         self.on_select_callback = None
+        self.on_context_menu_callback = None
 
         for child in self.findChildren(QWidget):
             child.installEventFilter(self)
 
     def eventFilter(self, obj, event):
         if event.type() == QEvent.Type.MouseButtonPress:
-            if self.on_select_callback:
-                self.on_select_callback(self)
+            if event.button() != Qt.MouseButton.RightButton:
+                if self.on_select_callback:
+                    self.on_select_callback(self)
+        elif event.type() == QEvent.Type.ContextMenu:
+            if self.on_context_menu_callback:
+                self.on_context_menu_callback(self, event.globalPos())
+            return True
         return False
 
     def mousePressEvent(self, event):
-        if self.on_select_callback:
-            self.on_select_callback(self)
+        if event.button() != Qt.MouseButton.RightButton:
+            if self.on_select_callback:
+                self.on_select_callback(self)
         super().mousePressEvent(event)
 
+    def contextMenuEvent(self, event):
+        if self.on_context_menu_callback:
+            self.on_context_menu_callback(self, event.globalPos())
+
     def apply_color(self, hex_color, selected=False):
         self.current_color = hex_color
         border = "#00ff88" if selected else "rgba(0,0,0,0.3)"