[Bug]: 调用FaseMCP编写的MCP时会导致tool result文件里写两份重复数据

## QwenPaw Version

2.1.0 b4

## Description

When the data returned by MCP exceeds the truncation threshold, the Tool Result truncation will be triggered. Then, the Tool Result file will contain two duplicate copies of data — one unstructured copy on the first line, and one formatted copy starting from the second line.

The root cause is that the _blocks_from_value function in the src\qwenpaw\drivers\adapters\agentscope_tool.py file writes both the structuredContent and content fields into the result.

**Related PR(s):** #(optional)

**Security considerations:** [If applicable, e.g. auth, env/config exposure]

## Component(s) Affected

- [x] Core / Backend (app, agents, config, providers, utils, local_models)
- [x] Console (frontend web UI)

## Environment

- **QwenPaw version:** [e.g. 0.x.x or git commit]
- **OS:** [e.g. macOS 14, Ubuntu 22.04, Windows 11]
- **Install method:** [pip / one-line install / Docker / from source]
- **Python version (if applicable):** [e.g. 3.10]

## Steps to Reproduce

As shown above

## Actual vs Expected

- **Actual:**
- **Expected:**

## Logs / Screenshots

[Paste relevant log output or attach screenshots. Use code blocks for logs.]

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## Additional Notes

[Optional: workarounds, similar issues, etc.]