Add configuration option to control default expand/collapse state of tool output blocks

Feature Description

Add a configuration option to control whether tool output blocks (thinking blocks, context blocks) are expanded or collapsed by default in the terminal UI.

Currently in v0.26.24+, these blocks are collapsed by default to prevent "streaming flicker" and keep the UI clean. While this is a good default, some users prefer to see the full output without manually toggling with Ctrl+O each time.

Proposed solution:

• Add a defaultExpandOutput boolean option to ~/.commandcode/config.json
• Default value: false (current behavior)
• When set to true, tool output blocks would be expanded by default

Use Case

This would benefit users who:

• Need to see the full AI reasoning/context for debugging or learning purposes
• Work in environments where manually expanding blocks adds friction to their workflow
• Prefer transparency in AI interactions and want to review all outputs
• Are reviewing complex multi-step operations where collapsing hides important context

Additional Context

This is a feature request stemming from the v0.26.24 release which intentionally collapsed these blocks by default. The current workaround is using Ctrl+O to toggle, but a configuration option would provide flexibility without requiring action on every session.

Priority: Important for my workflow

首先定位 ~/.commandcode/config.json 的配置处理逻辑，以及控制工具输出块和 Ctrl+O 切换的终端 UI 入口点。在保留当前默认折叠状态的同时，添加 defaultExpandOutput 行为，然后验证将其设置为 true 会以展开 thinking 块和上下文块的状态启动会话。