phsl / new-api

- Remove system name display from homepage title
- Replace with unified gateway branding: "统一的大模型接口网关"
- Add subtitle highlighting key benefits: price, stability, no subscription
- Implement language-specific title rendering:
  - English: Two-line layout ("The Unified" / "LLMs API Gateway")
  - Chinese: Single-line layout for better readability
- Increase title font sizes for better visual hierarchy
- Adjust vertical padding for improved centering
- Enhance overall visual appeal and user experience

This update modernizes the homepage presentation and provides better
localization support for different language preferences.