frontend: Improve High DPI support and scaling

This patch enhances High DPI support across the Qt frontend with the following improvements:

**Windows DPI Awareness:**
- Add shellscalingapi.h include for Windows DPI functions
- Implement Per Monitor DPI Awareness (Windows 8.1+) and Per Monitor v2 DPI Awareness (Windows 10+)
- Use SetProcessDPIAware() and SetProcessDpiAwareness() for better multi-monitor scaling
- Dynamically load shcore.dll to access modern DPI awareness APIs

**Configuration Dialog Enhancements:**
- Add comprehensive High DPI responsive CSS media queries for different DPI levels (192dpi, 240dpi)
- Scale UI elements (buttons, comboboxes, line edits, checkboxes, radio buttons) based on screen DPI
- Improve scroll area styling with proper scrollbar theming for high DPI displays
- Set proper window attributes for scaling (WA_TranslucentBackground, WA_NoSystemBackground)
- Calculate logical window size based on device pixel ratio for accurate scaling

**UI Improvements:**
- Enhanced scroll area styling with custom scrollbar appearance
- Better visual feedback with hover effects on scrollbar handles
- Improved spacing and sizing for high DPI displays
- Set proper window modality and title for configuration dialog

These changes provide better visual quality and usability on high DPI displays, particularly on Windows systems with multiple monitors or high-resolution screens. The scaling is now more accurate and consistent across different display configurations.

Signed-off-by: Zephyron <zephyron@citron-emu.org>

src/citron/configuration/configure_dialog.cpp

@@ -43,7 +43,60 @@ QScrollArea* CreateScrollArea(QWidget* widget) {
     scroll_area->setFrameShape(QFrame::NoFrame);
     scroll_area->setHorizontalScrollBarPolicy(Qt::ScrollBarAsNeeded);
     scroll_area->setVerticalScrollBarPolicy(Qt::ScrollBarAsNeeded);
-    scroll_area->setStyleSheet(QLatin1String("QScrollArea { border: none; background-color: #2b2b2b; }"));
+
+    // High DPI support: Scroll area will inherit scaling from parent
+
+    // Set style with high DPI aware styling
+    scroll_area->setStyleSheet(QLatin1String(
+        "QScrollArea { "
+        "border: none; "
+        "background-color: #2b2b2b; "
+        "}"
+        "QScrollArea > QWidget > QWidget { "
+        "background-color: #2b2b2b; "
+        "}"
+        "QScrollBar:vertical { "
+        "background-color: #3d3d3d; "
+        "width: 14px; "
+        "border-radius: 7px; "
+        "margin: 2px; "
+        "}"
+        "QScrollBar::handle:vertical { "
+        "background-color: #5d5d5d; "
+        "border-radius: 6px; "
+        "min-height: 30px; "
+        "margin: 1px; "
+        "}"
+        "QScrollBar::handle:vertical:hover { "
+        "background-color: #4a9eff; "
+        "}"
+        "QScrollBar::add-line:vertical, QScrollBar::sub-line:vertical { "
+        "border: none; "
+        "background: none; "
+        "height: 0px; "
+        "}"
+        "QScrollBar:horizontal { "
+        "background-color: #3d3d3d; "
+        "height: 14px; "
+        "border-radius: 7px; "
+        "margin: 2px; "
+        "}"
+        "QScrollBar::handle:horizontal { "
+        "background-color: #5d5d5d; "
+        "border-radius: 6px; "
+        "min-width: 30px; "
+        "margin: 1px; "
+        "}"
+        "QScrollBar::handle:horizontal:hover { "
+        "background-color: #4a9eff; "
+        "}"
+        "QScrollBar::add-line:horizontal, QScrollBar::sub-line:horizontal { "
+        "border: none; "
+        "background: none; "
+        "width: 0px; "
+        "}"
+    ));
+
     return scroll_area;
 }
 
@@ -81,16 +134,28 @@ ConfigureDialog::ConfigureDialog(QWidget* parent, HotkeyRegistry& registry_,
     setWindowFlags(Qt::Dialog | Qt::WindowTitleHint | Qt::WindowSystemMenuHint |
                    Qt::WindowMinMaxButtonsHint | Qt::WindowCloseButtonHint);
 
+    // High DPI support: Set proper attributes for scaling
+    setAttribute(Qt::WA_TranslucentBackground, false);
+    setAttribute(Qt::WA_NoSystemBackground, false);
+    setAttribute(Qt::WA_DontShowOnScreen, false);
+
     ui->setupUi(this);
 
     // Set size policy and enable resizing
     setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
 
-    // Get screen geometry and set to fullscreen
+    // Get screen geometry and set to fullscreen with high DPI awareness
     QScreen* screen = QApplication::primaryScreen();
     if (screen) {
         QRect screenGeometry = screen->availableGeometry();
-        setGeometry(screenGeometry);
+
+        // Calculate logical size based on device pixel ratio for high DPI support
+        qreal devicePixelRatio = screen->devicePixelRatio();
+        int logicalWidth = static_cast<int>(screenGeometry.width() / devicePixelRatio);
+        int logicalHeight = static_cast<int>(screenGeometry.height() / devicePixelRatio);
+
+        // Set geometry using logical units
+        setGeometry(0, 0, logicalWidth, logicalHeight);
         showMaximized(); // Start maximized/fullscreen
     }