feat(coding_agent_rl): add SWE-bench harness evaluation path

[aoshen02]

Summary

Add swebench_metadata as a third evaluation route in sandbox.evaluate(), alongside the existing swepro and eval_cmd paths. This allows coding_agent_rl to grade SWE-bench Verified instances directly using the official swebench harness.

Changes

• docker/Dockerfile: add uni-agent (source install, --no-deps) and swebench Python packages
• examples/coding_agent_rl/sandbox.py: add swebench_metadata param to evaluate(), add _run_swebench_eval() — reuses uni_agent.reward.swe_bench._make_eval_script_list for eval script generation, standard swebench grading API for result parsing
• examples/coding_agent_rl/generate.py: pass swebench_metadata through _metadata() and the evaluate() call site

Evaluation priority

swepro           → SWEPro custom scripts (existing, unchanged)
swebench_metadata → SWE-bench official harness (new)
eval_cmd         → shell command fallback (existing, unchanged)

Context

Validated on 500-instance SWE-bench Verified eval with Qwen3.6-35B-A3B: uniagent mode 71.3% (355/498), matching the official 71.6%.

Test plan

• `docker build` completes
• `python -c "from uni_agent.reward.swe_bench import _make_eval_script_list; print('ok')"` inside container
• Run a small SWE-bench eval with `swebench_metadata` in sample metadata

🤖 Generated with Claude Code

[jingshenghang]

There is an import error with uni-agent package.

Python 3.12.3 (main, Mar  3 2026, 12:15:18) [GCC 13.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import uni_agent
>>> from uni_agent.reward.swe_bench import make_eval_script, parse_eval_output
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.12/dist-packages/uni_agent/reward/swe_bench.py", line 21, in <module>
    from uni_agent.interaction import AgentEnv
  File "/usr/local/lib/python3.12/dist-packages/uni_agent/interaction/__init__.py", line 1, in <module>
    from .env import AgentEnv, AgentEnvConfig
  File "/usr/local/lib/python3.12/dist-packages/uni_agent/interaction/env.py", line 7, in <module>
    from swerex.exceptions import BashIncorrectSyntaxError, CommandTimeoutError
ModuleNotFoundError: No module named 'swerex'
>>>

[jingshenghang]

Hi, our refactoring of the agent framework has been merged into the main branch. Welcome pull requests based on our latest code.

#2005

[aoshen02]

Great, will try.