text: Title: [Feature] Allow Serving Requests During CUDA Graph Capture
  Body: ### Checklist
  
  - [x] 1. If the issue you raised is not a feature but a question, please raise a discussion at https://github.com/sgl-project/sglang/discussions/new/choose Otherwise, it will be closed.
  - [x] 2. Please use English, otherwise it will be closed.
  
  ### Motivation
  
  #### Background
  
  When `--enable-cuda-graph`, service restart (after crashes/unexpected exits) currently requires about 10-minute CUDA Graph capture process before becoming operational (longer with torch.compile enabled). This creates significant service downtime despite even with external health check and automatic restart, unless hot-standbys are deployed.
  
  I raised this question in community discussion group and received reply from @ baizhou: Theoretically feasible to let model runner choose whether to replay existing CUDA Graph.
  
  #### Requested Feature
  
  Add an option or fallback mechanism to allow serving requests without CUDA Graph replay during initialization, prioritizing availability over performance.
  
  #### Discussion
  
  I am open to discussing the details further and would appreciate any thoughts on implementation from the community. Thank you.
  
  ### Related resources
  
  _No response_