Introduce style guide

[zhzhuang-zju]

What would you like to be added:

Thanks to @mohamedawnallah for introducing Gemini Code Review! Its adoption over the past period has significantly improved our code maintenance efficiency. During code reviews, I’ve also realized that a consistent code style is crucial—it's often not a matter of right or wrong, but of shared conventions and team preferences.

By establishing a Style Guide, we can:

• Codify the project’s accumulated coding practices and stylistic preferences;
• Leverage Gemini Code Review to automatically enforce consistency;
• Clearly communicate these standards to developers via our website, improving code alignment and reducing rework.

The following tasks are proposed:

• Add a Style Guide docs in the website repository; (@zhzhuang-zju add karmada code style guide website#922)
• Add a /.gemini/styleguide.md file in the karmada repository.

[zhzhuang-zju]

/assign