Expand README with comprehensive SDK and CLI documentation

- Update Quick Start to use qwen-plus with messages format
- Add Supported Models table with latest models (qwen3.7, wan2.7, etc.)
- Add SDK Features section: Generation, MultiModal, Embedding, ReRank,
  Image/Video synthesis, TTS, ASR, Tokenization, Application, FineTune,
  Deployments, Assistants, OpenAI-compatible interface
- Add CLI Reference: generation, files, ft, deployments, oss, rl commands
- Keep existing Installation, API Key, Logging, Output, License sections

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: zhansheng.lzs