docs: 完善文档引用和安装说明

主要变更：
1. README.md 和 README_CN.md
   - 添加 COMMAND_SPEC.md 引用链接
   - 区分用户友好参考和技术规范

2. GETTING_STARTED.md
   - 添加 Skill 系统介绍章节
   - 添加 UI 设计工作流介绍
   - 包含 prompt-enhancer 使用示例
   - 包含 explore-auto 和 imitate-auto 示例

3. INSTALL.md 和 INSTALL_CN.md
   - 添加推荐系统工具安装说明（ripgrep, jq）
   - 添加 MCP 工具安装说明（Exa, Code Index, Chrome DevTools）
   - 添加可选 CLI 工具说明（Gemini, Codex, Qwen）
   - 提供各平台安装命令和验证步骤
   - 标注必需和可选工具

改进效果：
- 用户可快速找到技术规范文档
- 新手指南更完整，覆盖高级功能
- 安装文档更详细，包含所有依赖工具

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

GETTING_STARTED.md

@@ -273,6 +273,47 @@ This command will:
 
 ---
 
+## Advanced Usage: Agent Skills
+
+Agent Skills are modular, reusable capabilities that extend the AI's functionality. They are stored in the `.claude/skills/` directory and are invoked automatically by the model based on your request.
+
+### How Skills Work
+
+-   **Model-Invoked**: Unlike slash commands, you don't call Skills directly. The AI decides when to use a Skill based on its understanding of your goal.
+-   **Contextual**: Skills provide specific instructions, scripts, and templates to the AI for specialized tasks.
+-   **Example**: The built-in `prompt-enhancer` skill is triggered when you use the `--enhance` flag, automatically refining your prompt for better results.
+
+```bash
+# Using a command that triggers the prompt-enhancer skill
+/cli:analyze --enhance "check for security issues"
+```
+
+In this case, the `prompt-enhancer` skill activates to expand your brief request into a detailed, structured prompt for the security analysis.
+
+---
+
+## Advanced Usage: UI Design Workflow
+
+CCW includes a powerful, multi-phase workflow for UI design and prototyping, capable of generating complete design systems and interactive prototypes from simple descriptions or reference images.
+
+### Key Commands
+
+-   `/workflow:ui-design:explore-auto`: An exploratory workflow that generates multiple, distinct design variations based on a prompt.
+-   `/workflow:ui-design:imitate-auto`: A replication workflow that creates high-fidelity prototypes from reference URLs.
+
+### Example: Generating a UI from a Prompt
+
+You can generate multiple design options for a web page with a single command:
+
+```bash
+# This command will generate 3 different style and layout variations for a login page.
+/workflow:ui-design:explore-auto --prompt "A modern, clean login page for a SaaS application" --targets "login" --style-variants 3 --layout-variants 3
+```
+
+After the workflow completes, it provides a `compare.html` file, allowing you to visually review and select the best design combination.
+
+---
+
 ## ❓ Troubleshooting
 
 -   **Problem: Prompt shows "No active session found"**