Enhance skill generator documentation and templates

- Updated Phase 1 and Phase 2 documentation to include next phase links and data flow details.
- Expanded Phase 5 documentation to include comprehensive validation and README generation steps, along with validation report structure.
- Added purpose and usage context sections to various action and script templates (e.g., autonomous-action, llm-action, script-bash).
- Improved commands management by simplifying the command scanning logic and enabling/disabling commands through renaming files.
- Enhanced dashboard command manager to format group names and display nested groups with appropriate icons and colors.
- Updated LiteLLM executor to allow model overrides during execution.
- Added action reference guide and template reference sections to the skill-tuning SKILL.md for better navigation and understanding.

.claude/skills/skill-generator/templates/skill-md.md

@@ -2,6 +2,20 @@
 
 用于生成新 Skill 入口文件的模板。
 
+## Purpose
+
+生成新 Skill 的入口文件 (SKILL.md)，作为 Skill 的主文档和执行入口点。
+
+## Usage Context
+
+| Phase | Usage |
+|-------|-------|
+| Phase 2 (Structure Generation) | 创建 SKILL.md 入口文件 |
+| Generation Trigger | `config.execution_mode` 决定架构图样式 |
+| Output Location | `.claude/skills/{skill-name}/SKILL.md` |
+
+---
+
 ## ⚠️ 重要：YAML Front Matter 规范
 
 > **CRITICAL**: SKILL.md 文件必须以 YAML front matter 开头，即以 `---` 作为文件第一行。