fix: update README files to enhance installation instructions and bad…

[LinJHS]

This pull request updates both the Chinese (README.md) and English (README_EN.md) documentation to improve clarity, provide better installation instructions, and update project badges. The main focus is to make it easier for users to get started, especially by highlighting the new executable downloads and clarifying installation methods.

Documentation improvements:

• Added a visually centered header section with improved project badges for PyPI version, Python version, downloads, and license in both README.md and README_EN.md. [1] [2]
• Updated installation instructions to recommend downloading a pre-built executable for Windows, macOS, and Linux, including step-by-step usage guidance for each platform. [1] [2]
• Clarified and separated installation methods: now clearly distinguishes between using the executable and installing via pip, with improved explanations for both. [1] [2]
• Fixed the GitHub repository URL in the source installation instructions to use the correct LinJHS/oss-cleaner repo. [1] [2]
• Updated section titles and descriptions for better readability and to match the new installation flow. [1] [2]…ge formatting