[Bug]: qwenpaw task 命令 _run_task() 中 ctx.workspace=None

## QwenPaw Version

2.1.0

## Description

qwenpaw task 命令存在 bug — _run_task() 中 ctx.workspace=None，导致 AgentBuilder._get_local_workspace() 返回 None，工具列表为空（tools=0）。

WEB 后台通过 Workspace 类正确初始化了 QwenPawLocalWorkspace，工具正常加载。

Trace the qwenpaw task command into _run_task(), then inspect how ctx.workspace is initialized and how AgentBuilder._get_local_workspace() uses it. Compare this path with the Web backend’s Workspace initialization of QwenPawLocalWorkspace. Done means the CLI task has a workspace and the tools load instead of reporting tools=0.

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