[Fonts] Add per-purpose font section to palette editor (#7536)

* [Fonts] Add per-purpose font section to palette editor

* [Fonts] Make the editor's fallback and Reset preview-independent

- Add ThemeManager::defaultAppFont(), which resolves an unset role against the
  startup font instead of currentFonts, and use it in FontGridWidget::loadFonts
  so the grid never shows the live preview as the theme's default.
- Reload the live theme in PaletteEditorDialog::onReset before re-reading the
  grid, so Reset restores the saved fonts before loadFonts resolves fallbacks.

---------

Co-authored-by: Lukas Brübach <Bruebach.Lukas@bdosecurity.de>

cockatrice/src/interface/palette_editor/font_grid_widget.h

@@ -0,0 +1,43 @@
+#ifndef COCKATRICE_FONT_GRID_WIDGET_H
+#define COCKATRICE_FONT_GRID_WIDGET_H
+
+#include "../theme_config.h"
+
+#include <QMap>
+#include <QWidget>
+#include <qtmetamacros.h>
+
+class QFontComboBox;
+class QGridLayout;
+class QLabel;
+class QSpinBox;
+
+// Per-role font editors — one (family, point size) row per AppFont::Role.
+// Owns the load/read round-trip for FontConfig but has no file I/O, mirroring
+// PaletteGridWidget. Only family and point size are edited; weight and italic
+// stay caller-side concerns and are stripped when reading back.
+class FontGridWidget : public QWidget
+{
+    Q_OBJECT
+public:
+    explicit FontGridWidget(QWidget *parent = nullptr);
+
+    void loadFonts(const FontConfig &cfg);
+    FontConfig currentFontConfig() const;
+    void retranslateUi();
+
+signals:
+    void fontsChanged();
+
+private:
+    struct FontRow
+    {
+        QLabel *label = nullptr;
+        QFontComboBox *familyCombo = nullptr;
+        QSpinBox *sizeSpin = nullptr;
+    };
+
+    QMap<AppFont::Role, FontRow> fontRows;
+};
+
+#endif // COCKATRICE_FONT_GRID_WIDGET_H