Auto-detect and prefer user-installed CLI tools over built-in

### Describe the feature or problem you'd like to solve

The agent has no mechanism to discover equivalent tools on PATH to either opt for them first or use them as a fallback. It continues with a failing or inferior tool

### Proposed solution

- Reduces friction
- Reduces wasted turns
- It uses the tools that I use so I can easily trace what happened

### Example prompts or workflows

- "Find all usages of interface across this repo"
- "Lint all the modified typescript files"
- "Search this project for todo comments and summarize them"
- "Run tests for this module/component. Iterate until they pass"
- "Find all files larger than 1 mb in this directory and sub directories

### Additional context

_No response_

该 issue 未指出用于 PATH 发现和工具偏好的文件、测试或入口点。首先定位 CLI 内置的工具定义和命令执行流程；完成的标准是，能够发现等效的用户安装工具，并在所列工作流中优先使用它们或将其用作回退方案。

由索引模型根据 Issue 内容生成。