[Bug] non-JSON request would lose body in http_proxy endpoint

[Dengsheng-wzh]

Bug Description

Steps to Reproduce

Expected Behavior

Actual Behavior

Error Logs

Environment Information

• OS: [e.g. Ubuntu 22.04, macOS 13.0, Windows 11]
• Python Version: [e.g. 3.11.5]
• ROCK Version: [e.g. 0.2.0]
• Installation Method: [e.g. pip install rl-rock, source installation with uv]
• Docker Version: [e.g. 24.0.6] (if using sandbox features)
• Deployment Type: [e.g. local, distributed, ray]

ROCK Configuration

• Runtime Environment Type: [e.g. uv, pip, conda]
• Sandbox Image: [e.g. python:3.11, custom image]
• Resource Allocation: [e.g. memory=8g, cpus=2.0]

Component Affected

• Sandbox
• Actions
• Deployments
• SDK & API
• Envhub
• CLI
• Performance & Optimization
• Documentation & Examples