merge upstream/master: logging pragma, screenshot retrieval, nbsp fix

Merge 3 upstream commits into mod/master:
- feat: Allow screenshot retrieval from device (#820)
- feat: Add central logging pragma (#843)
- fix: Account for nbsp character as non-breaking space (#757)

Conflict resolution:
- src/main.cpp: kept mod's HalPowerManager + upstream's Logging/screenshot
- SleepActivity.cpp: kept mod's letterbox fill rework, applied LOG_* pattern

Additional changes for logging compatibility:
- Converted remaining Serial.printf calls in mod files to LOG_* macros
  (HalPowerManager, BookSettings, BookmarkStore, GfxRenderer)
- Added ENABLE_SERIAL_LOG and LOG_LEVEL=2 to [env:mod] build flags

Co-authored-by: Cursor <cursoragent@cursor.com>

src/util/BookSettings.cpp

@@ -1,7 +1,7 @@
 #include "BookSettings.h"
 
 #include <HalStorage.h>
-#include <HardwareSerial.h>
+#include <Logging.h>
 #include <Serialization.h>
 
 namespace {
@@ -37,15 +37,15 @@ BookSettings BookSettings::load(const std::string& cachePath) {
   } while (false);
 
   f.close();
-  Serial.printf("[%lu] [BST] Loaded book settings from %s (letterboxFill=%d)\n", millis(), filePath(cachePath).c_str(),
-                settings.letterboxFillOverride);
+  LOG_DBG("BST", "Loaded book settings from %s (letterboxFill=%d)", filePath(cachePath).c_str(),
+          settings.letterboxFillOverride);
   return settings;
 }
 
 bool BookSettings::save(const std::string& cachePath, const BookSettings& settings) {
   FsFile f;
   if (!Storage.openFileForWrite("BST", filePath(cachePath), f)) {
-    Serial.printf("[%lu] [BST] Could not save book settings!\n", millis());
+    LOG_ERR("BST", "Could not save book settings!");
     return false;
   }
 
@@ -55,6 +55,6 @@ bool BookSettings::save(const std::string& cachePath, const BookSettings& settin
   // New fields added here
   f.close();
 
-  Serial.printf("[%lu] [BST] Saved book settings to %s\n", millis(), filePath(cachePath).c_str());
+  LOG_DBG("BST", "Saved book settings to %s", filePath(cachePath).c_str());
   return true;
 }