fix: truncate long output

[dexhunter]

Some execution results have too long output and leading the 413 error

╭───────────────────────────── Optimization Error ─────────────────────────────╮
│ Error: 413 Client Error: Request Entity Too Large for url:                   │
│ https://api.weco.ai/v1/runs/a0fa10d7-3e4e-487b-b52e-5f8ba4cc0c68/suggest     │
╰──────────────────────────────────────────────────────────────────────────────╯

[Copilot]

Pull Request Overview

This PR adds output truncation to prevent oversized responses and applies it to the evaluation runner to avoid 413 errors.

• Introduce DEFAULT_MAX_LINES and DEFAULT_MAX_CHARS constants.
• Implement truncate_output helper to trim by lines and/or characters with a descriptive prefix.
• Update run_evaluation to return the truncated output.

Comments suppressed due to low confidence (1)

weco/utils.py:131

• Add unit tests for truncate_output to cover scenarios where only lines exceed, only characters exceed, both conditions, and no truncation.

def truncate_output(output: str, max_lines: int = DEFAULT_MAX_LINES, max_chars: int = DEFAULT_MAX_CHARS) -> str:

[DhruvSrikanth]

Looks good to me! Feel free to merge @dexhunter