Replace Iosevka with JetBrains Mono, fix scrollbar and inline edit UX

- Replace embedded Iosevka font with JetBrains Mono as default font
- Fix wide horizontal scrollbar by enabling SCI_SETSCROLLWIDTHTRACKING
- Remove 28-char trailing whitespace padding from all lines
- Fix arrow keys not collapsing selection in inline edit mode
- Dim struct/array braces ({ and };) to match hex node styling
- Resize margin immediately on font change

src/controller.cpp

@@ -1496,7 +1496,7 @@ void RcxController::showTypeSelectorPopup(RcxEditor* editor) {
 
     // Get font with zoom
     QSettings settings("ReclassX", "ReclassX");
-    QString fontName = settings.value("font", "Consolas").toString();
+    QString fontName = settings.value("font", "JetBrains Mono").toString();
     QFont font(fontName, 12);
     font.setFixedPitch(true);
     auto* sci = editor->scintilla();