feat(skill): refactor skill system with router + references structure (#192)

Refactors SKILL.md into a router + reference documentation system:
- Main SKILL.md now contains routing table and quick commands
- Detailed docs split into references/ (search, social, career, dev, web, video)
- CLI skill install copies entire directory including references/
- Resolves conflicts with recent merges (#210, #213)
- Fixes xreach→bird in quick commands

Original PR by @Citrus086, merged with conflict resolution.

Co-Authored-By: Citrus086 <Citrus086@users.noreply.github.com>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

agent_reach/skill/references/dev.md

@@ -0,0 +1,62 @@
+# 开发工具
+
+GitHub CLI 
+
+## GitHub (gh CLI)
+
+GitHub 官方命令行工具，用于仓库、Issue、PR、Actions、Release 以及 API 访问。
+
+```bash
+# 认证
+gh auth login
+gh auth status
+
+# 搜索
+gh search repos "query" --sort stars --limit 10
+gh search code "query" --language python
+
+# 仓库
+gh repo view owner/repo
+gh repo clone owner/repo
+gh repo create my-repo --private
+gh repo fork owner/repo
+gh repo fork owner/repo --clone
+gh repo sync owner/repo
+
+# Issues
+gh issue list -R owner/repo --state open
+gh issue view 123 -R owner/repo
+gh issue create -R owner/repo --title "Title" --body "Body"
+
+# Pull Requests
+gh pr list -R owner/repo --state open
+gh pr view 123 -R owner/repo
+gh pr create -R owner/repo --title "Title" --body "Body"
+gh pr checks 123 --repo owner/repo
+
+# Actions / CI
+gh run list --repo owner/repo --limit 10
+gh run view <run-id> --repo owner/repo
+gh run view <run-id> --repo owner/repo --log-failed
+gh workflow list --repo owner/repo
+
+# Releases
+gh release list -R owner/repo
+gh release create v1.0.0
+
+# API
+gh api /user
+gh api repos/owner/repo
+
+# JSON 输出
+gh issue list --repo owner/repo --json number,title --jq '.[] | "\(.number): \(.title)"'
+```
+
+
+## 选择指南
+
+| 工具 | 来源 | 用途 |
+|-----|------|------|
+| gh CLI | agent-reach | Git 操作 |
+| zread | my-mcp-tools | 读仓库内容 |
+| context7 | my-mcp-tools | 查技术文档 |