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>

platformio.ini

@@ -54,6 +54,9 @@ extends = base
 build_flags =
   ${base.build_flags}
   -DCROSSPOINT_VERSION=\"${crosspoint.version}-dev\"
+  -DENABLE_SERIAL_LOG
+  -DLOG_LEVEL=2 ; Set log level to debug for development builds
+
 
 [env:mod]
 extends = base
@@ -62,15 +65,30 @@ extra_scripts =
   pre:scripts/inject_mod_version.py
 build_flags =
   ${base.build_flags}
+  -DENABLE_SERIAL_LOG
+  -DLOG_LEVEL=2 ; Set log level to debug for mod builds
 
 [env:gh_release]
 extends = base
 build_flags =
   ${base.build_flags}
   -DCROSSPOINT_VERSION=\"${crosspoint.version}\"
+  -DENABLE_SERIAL_LOG
+  -DLOG_LEVEL=0 ; Set log level to error for release builds  
 
 [env:gh_release_rc]
 extends = base
 build_flags =
   ${base.build_flags}
   -DCROSSPOINT_VERSION=\"${crosspoint.version}-rc+${sysenv.CROSSPOINT_RC_HASH}\"
+  -DENABLE_SERIAL_LOG
+  -DLOG_LEVEL=1 ; Set log level to info for release candidate builds  
+
+[env:slim]
+extends = base
+build_flags =
+  ${base.build_flags}
+  -DCROSSPOINT_VERSION=\"${crosspoint.version}-slim\"
+  ; serial output is disabled in slim builds to save space
+  -UENABLE_SERIAL_LOG
+