feat(market): 为外部技能补充图标 (#50)

## Summary / 摘要

Add inline SVG icons to all 20 external pointer skills, so their cards
no longer fall back to an empty icon. The market catalog version is
bumped from `1.2.8` to `1.2.9`.

为全部 20 个外部 pointer skill 补齐内联 SVG 图标，市场卡片不再显示为空；市场版本由 `1.2.8` 升至
`1.2.9`。

## Compatibility / 兼容性

Depends on desirecore/desirecore#1177, which permits the `icon` field in
strict pointer-entry validation and forwards it through the offline
list/detail responses. That PR must merge first.

## Skill → icon screenshot / Skill 与图标截图

The preview labels every card with its display name and id.

![External skill icon
preview](https://raw.githubusercontent.com/desirecore/market/feat/external-skill-icons/docs/assets/external-skill-icons-v1.2.9.svg)

Covered skills: `agent-reach`, `ai-news-radar`, `amap-jsapi-skill`,
`dingtalk-api`, `flyai-skill`, `follow-builders`,
`ian-xiaohei-illustrations`, `karpathy-guidelines`, `khazix-skills`,
`larksuite-cli`, `last30days`, `luckin-my-coffee`, `mattpocock-skills`,
`minimax-image-gen`, `minimax-tts`, `mt-paotui-for-client`,
`netease-skills`, `taste-skill`, `wechatpay-skills`, and `wecom-cli`.

## Validation / 验证

- `uv run scripts/i18n/validate-i18n.py`
- `uv run scripts/i18n/translate.py --check`
- Parsed all 20 `entry.json` icons as SVG XML
- `git diff --check`
- Rendered the committed preview asset locally

skills/agent-reach/entry.json

@@ -2,6 +2,7 @@
   "id": "agent-reach",
   "name": "Agent Reach",
   "category": "research",
+  "icon": "<svg xmlns=\"http://www.w3.org/2000/svg\" width=\"24\" height=\"24\" viewBox=\"0 0 24 24\" fill=\"none\"><circle cx=\"12\" cy=\"12\" r=\"7\" stroke=\"#2563EB\" stroke-width=\"1.7\"/><path d=\"M12 5V3m0 18v-2m7-7h2M3 12h2m11.9-4.9 1.4-1.4M5.7 18.3l1.4-1.4m9.8 1.4-1.4-1.4M5.7 5.7l1.4 1.4\" stroke=\"#2563EB\" stroke-width=\"1.7\" stroke-linecap=\"round\"/><circle cx=\"12\" cy=\"12\" r=\"2\" fill=\"#2563EB\"/></svg>",
   "tags": ["research", "web-search", "social-media", "twitter", "reddit", "youtube", "bilibili", "xiaohongshu"],
   "maintainer": {
     "name": "Panniantong",