Feat/sleep and refresh settings (#209)

## Summary

* **What is the goal of this PR?** (e.g., Fixes a bug in the user
authentication module, Implements the new feature for
  file uploading.)
* **What changes are included?**

## Additional Context

* Add any other information that might be helpful for the reviewer
(e.g., performance implications, potential risks, specific areas to
focus on).

---------

Co-authored-by: ratedcounsel <hello@ratedcounsel.com>
Co-authored-by: Dave Allie <dave@daveallie.com>

src/activities/reader/EpubReaderActivity.cpp

@@ -13,7 +13,7 @@
 #include "fontIds.h"
 
 namespace {
-constexpr int pagesPerRefresh = 15;
+// pagesPerRefresh now comes from SETTINGS.getRefreshFrequency()
 constexpr unsigned long skipChapterMs = 700;
 constexpr unsigned long goHomeMs = 1000;
 constexpr int topPadding = 5;
@@ -379,7 +379,7 @@ void EpubReaderActivity::renderContents(std::unique_ptr<Page> page, const int or
   renderStatusBar(orientedMarginRight, orientedMarginBottom, orientedMarginLeft);
   if (pagesUntilFullRefresh <= 1) {
     renderer.displayBuffer(EInkDisplay::HALF_REFRESH);
-    pagesUntilFullRefresh = pagesPerRefresh;
+    pagesUntilFullRefresh = SETTINGS.getRefreshFrequency();
   } else {
     renderer.displayBuffer();
     pagesUntilFullRefresh--;