feat: 添加 video-use 视频剪辑技能入口 (#192)

## Summary / 摘要

- Add a pinned Market pointer for the upstream `browser-use/video-use`
skill, with English and Chinese discovery text.
- Add catalog metadata for its MIT license, source provenance,
Python/ffmpeg prerequisites, and ElevenLabs Scribe API key and
usage-cost requirement.
- Keep the listing discovery-only until installation and governance
review are completed.
- Add the entry to Market statistics. No upstream skill code is
vendored.

- 新增固定到上游提交的 `browser-use/video-use` 市场入口及中英文介绍。
- 补充 MIT 许可、来源、Python/ffmpeg 前置条件，以及 ElevenLabs Scribe 密钥和可能产生的 API 费用。
- 完成安装与治理审查前，条目标记为仅供发现。
- 更新 Market 条目统计，不复制上游技能代码。

## Validation / 校验

- `uv run scripts/i18n/validate-i18n.py skills/video-use` — passed with
0 errors (existing catalog warnings remain).
- `uv run scripts/catalog/validate_catalog_metadata.py
--require-complete` — passed with 0 errors.
- `uv run scripts/i18n/translate.py --check` — passed.
- `git diff --check` — passed.

manifest.json

@@ -31,8 +31,8 @@
   "stats": {
     "totalAgents": 7,
     "totalTeams": 2,
-    "totalSkills": 72,
-    "lastUpdated": "2026-09-25"
+    "totalSkills": 73,
+    "lastUpdated": "2026-09-29"
   },
   "features": [
     "curated-index",