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/wechatpay-skills/entry.json

@@ -2,6 +2,7 @@
   "id": "wechatpay-skills",
   "name": "WeChat Pay Skills",
   "category": "business",
+  "icon": "<svg xmlns=\"http://www.w3.org/2000/svg\" width=\"24\" height=\"24\" viewBox=\"0 0 24 24\" fill=\"none\"><rect x=\"4\" y=\"6\" width=\"16\" height=\"12\" rx=\"2\" stroke=\"#2563EB\" stroke-width=\"1.7\"/><path d=\"M4 10h16m-8 4h4\" stroke=\"#2563EB\" stroke-width=\"1.7\" stroke-linecap=\"round\"/><circle cx=\"8\" cy=\"14\" r=\"1.5\" fill=\"#2563EB\"/></svg>",
   "tags": [
     "wechatpay-apiv3"
   ],