DolphinQt: Size adjustments in **Registers** widget based on selected debug font.

- Row height is no longer hardcoded to `24`; instead, the height is
  determined by the font height of the currently selected debug font.
- Header height has been reduced (a factor of the font height) as it
  only serves as a column resizer.
- A `OnDebugFontChanged()` slot has been connected to properly update
  the widget on debug font changes.

| Before | After |
| --- | --- |
| <img alt="Registers widget (before)" title="Registers widget (before)" src="https://github.com/user-attachments/assets/8a6644f9-1081-4ac8-9fff-c79ddb73e103" /> | <img alt="Registers widget (after)" title="Registers widget (after)" src="https://github.com/user-attachments/assets/67f799d0-8afd-4081-bb40-3d7a76ddc705" /> |

Source/Core/DolphinQt/Debugger/RegisterWidget.cpp

@@ -80,10 +80,10 @@ void RegisterWidget::CreateWidgets()
   m_table->setColumnCount(9);
 
   m_table->verticalHeader()->setVisible(false);
-  m_table->verticalHeader()->setDefaultSectionSize(24);
   m_table->setContextMenuPolicy(Qt::CustomContextMenu);
   m_table->setSelectionMode(QAbstractItemView::NoSelection);
-  m_table->setFont(Settings::Instance().GetDebugFont());
+
+  OnDebugFontChanged(Settings::Instance().GetDebugFont());
 
   QStringList empty_list;
 
@@ -106,7 +106,8 @@ void RegisterWidget::ConnectWidgets()
   connect(m_table, &QTableWidget::customContextMenuRequested, this,
           &RegisterWidget::ShowContextMenu);
   connect(m_table, &QTableWidget::itemChanged, this, &RegisterWidget::OnItemChanged);
-  connect(&Settings::Instance(), &Settings::DebugFontChanged, m_table, &RegisterWidget::setFont);
+  connect(&Settings::Instance(), &Settings::DebugFontChanged, this,
+          &RegisterWidget::OnDebugFontChanged);
 }
 
 void RegisterWidget::OnItemChanged(QTableWidgetItem* item)
@@ -115,6 +116,20 @@ void RegisterWidget::OnItemChanged(QTableWidgetItem* item)
     static_cast<RegisterColumn*>(item)->SetValue();
 }
 
+void RegisterWidget::OnDebugFontChanged(const QFont& font)
+{
+  if (m_table)
+  {
+    m_table->setFont(font);
+    const auto fontHeight = m_table->fontMetrics().height();
+    m_table->verticalHeader()->setDefaultSectionSize(fontHeight);
+
+    // Header height doesn't have to be great. As there are no labels, its only purpose is to make
+    // columns resizable.
+    m_table->horizontalHeader()->setFixedHeight(fontHeight * 5 / 4);
+  }
+}
+
 void RegisterWidget::ShowContextMenu()
 {
   QMenu* menu = new QMenu(this);

Source/Core/DolphinQt/Debugger/RegisterWidget.h

@@ -46,6 +46,7 @@ private:
 
   void ShowContextMenu();
   void OnItemChanged(QTableWidgetItem* item);
+  void OnDebugFontChanged(const QFont& font);
 
   void AddRegister(int row, int column, RegisterType type, std::string register_name,
                    std::function<u64()> get_reg, std::function<void(u64)> set_reg);