fix(demo): add fallback to internal model when external model data is missingIf no valid model data is provided, the system now checks if an internal model
should be used. This enhances the robustness of the demo pipeline by providing
a default behavior when essential data is not available.

fix: object cluster algorithm

modify readme.md

Improve the model loading mechanism in magic_pdf by implementing a Singleton
pattern to reduce redundant model instantiation. Additionally, enhance the
command-line interface to support input from list files, allowing batch
processing of multiple PDF documents.

Add Chinese translations to the feature request issue template to enhance
accessibility for Chinese-speaking users and facilitate their contributionto the project.

Add Chinese translations to the bug report issue template to improve accessibility
for Chinese-speaking users and make it easier for them to contribute to the project.

Introduce a Singleton pattern to manage custom models in the magic_pdf module.
This change improves the efficiency by ensuring that a single instance of the
custom model is created and reused, thereby reducing the overhead of multiple
instantiate calls for the same model configuration.

add ci