docs: sync model and image pricing updates

[ai-bankofai]

Summary

• sync DeepSeek V4 pricing rules and add DeepSeek Vision pricing/free API notice
• update GPT-5.6 Sol pricing and MiMo-V2.5 free-access details
• add GPT-Image-2 and Grok Imagine Image 2.0 model/pricing docs in English and Chinese
• split model navigation into language and image generation sections
• bump package version from 1.3.24 to 1.3.25

Validation

• yarn build
• git diff --check