[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.]

```
(paste logs here)
```

## Additional Notes

[Optional: workarounds, similar issues, etc.]

Start in src\qwenpaw\drivers\adapters\agentscope_tool.py at the _blocks_from_value function, focusing on how structuredContent and content are written when MCP data exceeds the truncation threshold. Confirm the truncation path and make sure the Tool Result file contains one copy rather than both unstructured and formatted data.

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