test: add local multi-turn coding agent smoke test

[aoshen02]

Summary

• add a local Docker sandbox adapter for coding-agent rollouts
• add a reproducible 10-task SWE-bench SymPy smoke test
• document the H200, Qwen3.5-27B, TP8, 256K-context setup
• persist per-task inputs, trajectories, patches, grading results, and sandbox events

Scope

This is a rollout-only local experiment. It is not registered in CI and does not change Vime runtime behavior.

Validation

• bash -n on both shell entrypoints
• Python syntax compilation for generate.py and sandbox.py
• JSONL validation: 10 unique task instances
• git diff --cached --check