Updated NcgEpubFile.open(String cID, String path) function:

• Added cID (Content ID) parameter to the NcgEpubFile.open() function.

• When the same Content ID is reused, internal file open and DRM info parsing are skipped, improving performance.

Added Multi-thread Support for NcgEpubFile:

• NcgEpubFile class now supports multi-threaded usage.

• Each NcgEpubFile instance must be operated by a single thread — multiple threads reading from the same open() call are not supported.

Updated NcgEpubFile.close() call behavior:

• close() should no longer be called immediately after each open(). Instead, call close() only when all file operations are complete.

• For contents sharing the same cID, use open() to open the next file without calling close() in between.

• Example: When an EPUB file contains multiple internal files, call open() for each file as needed, and call close() only once when all files within the EPUB have been processed.