Add three MIT community skill entries (agent-reach, ian-xiaohei-illustrations, khazix-skills) (#45)

## Summary

按 ADR-038《市场元数据注册表与两层技能模型》,以 `entry.json` pointer 形式收录三个第三方 community
skill。**仅登记元数据,正文全部留在各自源仓库**,不向 market 仓库 vendoring 任何源码/二进制。

| id | 源仓库 | license | stewardship | redistribution | category |
|----|--------|---------|-------------|----------------|----------|
| `agent-reach` |
[Panniantong/agent-reach](https://github.com/Panniantong/agent-reach) |
MIT | community | allowed | research |
| `ian-xiaohei-illustrations` |
[helloianneo/ian-xiaohei-illustrations](https://github.com/helloianneo/ian-xiaohei-illustrations)
| MIT | community | allowed | media |
| `khazix-skills` |
[KKKKhazix/khazix-skills](https://github.com/KKKKhazix/khazix-skills) |
MIT | community | allowed | productivity |

## Changes

- 新增 `skills/agent-reach/entry.json`(SKILL.md 位于 `agent_reach/skill`,已用
`source.path` 指向)
- 新增 `skills/ian-xiaohei-illustrations/entry.json`(SKILL.md 位于同名子目录,已用
`source.path` 指向)
- 新增 `skills/khazix-skills/entry.json`(多技能合集,指向仓库根)
- 三条 `source.ref` 均固定到源仓库当前 HEAD commit,保证可复现
- `manifest.json`:`stats.totalSkills` 45 → 48,`lastUpdated` 更新为
2026-07-09
- `README.md`:同步计数(external 15→18 / total 45→48)与外部条目列表

## Compliance (ADR-038)

- 三个源仓库均为 MIT,`redistribution: allowed`,可分发
- 未向 market 仓库引入任何 upstream 源码树 / zip / 二进制
- 字段遵循现有 `entry.json` 约定(参照 mattpocock-skills / netease-skills 等既有条目)

README.md

@@ -24,8 +24,8 @@ The market currently contains:
 
 - `1` Agent: `desirecore`
 - `30` local built-in skills with `SKILL.md`
-- `15` external skill entries with `entry.json`
-- `45` publishable skills in total (`SKILL.md` + `entry.json`)
+- `18` external skill entries with `entry.json`
+- `48` publishable skills in total (`SKILL.md` + `entry.json`)
 
 ## Skill Sources
 
@@ -44,10 +44,10 @@ xiaomi-tts, xlsx
 External entries are marketplace pointers to Git/Web/ZIP sources:
 
 ```text
-ai-news-radar, amap-jsapi-skill, dingtalk-api, flyai-skill,
-follow-builders, larksuite-cli, luckin-my-coffee, mattpocock-skills,
-minimax-image-gen, minimax-tts, mt-paotui-for-client, netease-skills,
-taste-skill, wechatpay-skills, wecom-cli
+agent-reach, ai-news-radar, amap-jsapi-skill, dingtalk-api, flyai-skill,
+follow-builders, ian-xiaohei-illustrations, khazix-skills, larksuite-cli,
+luckin-my-coffee, mattpocock-skills, minimax-image-gen, minimax-tts,
+mt-paotui-for-client, netease-skills, taste-skill, wechatpay-skills, wecom-cli
 ```
 
 ## Data Formats