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

src/CrossPointSettings.h

@@ -144,7 +144,7 @@ class CrossPointSettings {
   // Sleep screen cover filter
   uint8_t sleepScreenCoverFilter = NO_FILTER;
   // Apply information overlay with reading progress on sleep cover
-  uint8_t sleepCoverOverlay = 1;
+  uint8_t sleepCoverOverlay = 0;
   // Status bar settings (statusBar retained for migration only)
   uint8_t statusBar = FULL;
   uint8_t statusBarChapterPageCount = 1;