docs: improve README documentation structure and formatting

- Add table of contents with navigation links
- Unify language to English throughout the document
- Improve header hierarchy and section organization
- Enhance badge styling with proper links
- Standardize code block formatting (bash/php/sql)
- Add section separators for better readability
- Improve test documentation structure
- Add License section
- Clean up duplicate content

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Co-Authored-By: Claude <[email protected]>

Author: houaiai