Refactor sleep cover overlay: BookOverlayInfo struct, multi-line layout, 4 color modes (White/Gray/Black/Off)

src/activities/boot_sleep/SleepActivity.h

@@ -1,8 +1,19 @@
 #pragma once
+
+#include <string>
+
 #include "../Activity.h"
 
 class Bitmap;
 
+struct BookOverlayInfo {
+  std::string title;
+  std::string author;
+  std::string progressText;
+  std::string chapterName;
+  std::string progressSuffix;
+};
+
 class SleepActivity final : public Activity {
  public:
   explicit SleepActivity(GfxRenderer& renderer, MappedInputManager& mappedInput)
@@ -15,5 +26,5 @@ class SleepActivity final : public Activity {
   void renderCoverSleepScreen() const;
   void renderBitmapSleepScreen(const Bitmap& bitmap) const;
   void renderBlankSleepScreen() const;
-  std::string getBookOverlayText(const std::string& bookPath) const;
+  BookOverlayInfo getBookOverlayInfo(const std::string& bookPath) const;
 };