mod: Phase 3 — Re-port unmerged upstream PRs

Re-applied upstream PRs not yet merged to upstream/master:

- #1055: Byte-level framebuffer writes (fillPhysicalHSpan*,
  optimized fillRect/drawLine/fillRectDither/fillPolygon)
- #1027: Word-width cache (FNV-1a, 128-entry) and hyphenation
  early exit in ParsedText for 7-9% layout speedup
- #1068: Already present in upstream — URL hyphenation fix
- #1019: Already present in upstream — file extensions in browser
- #1090/#1185/#1217: KOReader sync improvements — binary credential
  store, document hash caching, ChapterXPathIndexer integration
- #1209: OPDS multi-server — OpdsBookBrowserActivity accepts
  OpdsServer, directory picker for downloads, download-complete
  prompt with open/back options
- #857: Dictionary activities already ported in Phase 1/2
- #1003: Placeholder cover already integrated in Phase 2

Also fixed: STR_OFF i18n string, include paths, replaced
Epub::isValidThumbnailBmp with Storage.exists, replaced
StringUtils::checkFileExtension with FsHelpers equivalents.

Made-with: Cursor

lib/hal/HalStorage.cpp

@@ -137,6 +137,9 @@ void HalFile::flush() { HAL_FILE_WRAPPED_CALL(flush, ); }
 size_t HalFile::getName(char* name, size_t len) { HAL_FILE_WRAPPED_CALL(getName, name, len); }
 size_t HalFile::size() { HAL_FILE_FORWARD_CALL(size, ); }          // already thread-safe, no need to wrap
 size_t HalFile::fileSize() { HAL_FILE_FORWARD_CALL(fileSize, ); }  // already thread-safe, no need to wrap
+bool HalFile::getModifyDateTime(uint16_t* pdate, uint16_t* ptime) {
+  HAL_FILE_WRAPPED_CALL(getModifyDateTime, pdate, ptime);
+}
 bool HalFile::seek(size_t pos) { HAL_FILE_WRAPPED_CALL(seekSet, pos); }
 bool HalFile::seekCur(int64_t offset) { HAL_FILE_WRAPPED_CALL(seekCur, offset); }
 bool HalFile::seekSet(size_t offset) { HAL_FILE_WRAPPED_CALL(seekSet, offset); }