Add firmware font size setting

Tactility/Include/Tactility/lvgl/Lvgl.h

@@ -1,5 +1,9 @@
 #pragma once
 
+namespace tt::settings::display {
+enum class FontSize;
+}
+
 namespace tt::lvgl {
 
 #ifdef ESP_PLATFORM
@@ -12,6 +16,9 @@ static constexpr auto* PATH_PREFIX = "A:/";
 
 bool isStarted();
 
+/** Applies the selected semantic text size to the LVGL theme and future widgets. */
+void applyFontSize(settings::display::FontSize fontSize);
+
 void start();
 
 void stop();

Tactility/Include/Tactility/settings/DisplaySettings.h

@@ -22,8 +22,16 @@ enum class ScreensaverType {
     Count           // Sentinel for bounds checking - must be last
 };
 
+enum class FontSize {
+    Small,
+    Default,
+    Large,
+    Count
+};
+
 struct DisplaySettings {
     Orientation orientation;
+    FontSize fontSize = FontSize::Default;
     uint8_t gammaCurve;
     uint8_t backlightDuty;
     bool backlightTimeoutEnabled;