port: upstream PR #1342 - Book Info screen, richer metadata, safer controls

Ports upstream PR #1342 (feat: Add Book Info screen, richer metadata,
and safer file-browser controls) with mod-specific adaptations:

- Parse and cache series, seriesIndex, description from EPUB OPF
- Bump book.bin cache version to 6 for new metadata fields
- Add BookInfoActivity (new screen) accessible via Right button in FileBrowser
- Add ManageBook menu via Left button in FileBrowser (replaces upstream hidden delete)
- Guard all delete/archive actions with ConfirmationActivity (10 call sites)
- Add inputArmed gating to ConfirmationActivity to prevent accidental confirmation
- Safe deserialization: readString now returns bool with MAX_STRING_LENGTH guard
- Add series field to RecentBooksStore with JSON and binary serialization
- Add i18n keys: STR_BOOK_INFO, STR_AUTHOR, STR_SERIES, STR_FILE_SIZE, etc.

Made-with: Cursor

lib/KOReaderSync/KOReaderDocumentId.cpp

@@ -20,8 +20,7 @@ std::string getFilename(const std::string& path) {
 std::string KOReaderDocumentId::getCacheFilePath(const std::string& filePath) {
   // Mirror the Epub cache directory convention so the hash file shares the
   // same per-book folder as other cached data.
-  return std::string("/.crosspoint/epub_") + std::to_string(std::hash<std::string>{}(filePath)) +
-         "/koreader_docid.txt";
+  return std::string("/.crosspoint/epub_") + std::to_string(std::hash<std::string>{}(filePath)) + "/koreader_docid.txt";
 }
 
 std::string KOReaderDocumentId::loadCachedHash(const std::string& cacheFilePath, const size_t fileSize,