fix: resolve mod build errors after upstream sync

- Update open-x4-sdk submodule to 9f76376 (BatteryMonitor ESP-IDF 5.x compat)
- Add RTC_NOINIT bounds check for logHead in Logging.cpp
- Add drawTextRotated90CCW to GfxRenderer for dictionary UI
- Add getWordXpos() accessor to TextBlock for dictionary word selection
- Fix bare include paths (ActivityResult.h, RenderLock.h) across 10 files
- Fix rvalue ref binding in setResult() lambdas (std::move pattern)
- Fix std::max type mismatch (uint8_t vs int) in EpubReaderActivity
- Fix FsFile forward declaration conflict in Dictionary.h
- Restore StringUtils::checkFileExtension() and sortFileList()
- Restore RecentBooksStore::removeBook()

Made-with: Cursor

src/RecentBooksStore.h

@@ -37,6 +37,8 @@ class RecentBooksStore {
   void updateBook(const std::string& path, const std::string& title, const std::string& author,
                   const std::string& coverBmpPath);
 
+  void removeBook(const std::string& path);
+
   // Get the list of recent books (most recent first)
   const std::vector<RecentBook>& getBooks() const { return recentBooks; }