feat: 新增 cloud-artifacts 包（Cloudflare Worker HTML artifact 托管）

POST /upload 鉴权上传 HTML 到 R2 返回 hash URL，GET /<7d|30d>/<id>.html
由 Worker 代理读取并直出 text/html。R2 lifecycle rule 自动 7/30 天删除。
独立服务，不被主 CLI 引用（类似 packages/remote-control-server/ 定位）。

Co-Authored-By: glm-5.2 <zai-org@claude-code-best.win>

packages/cloud-artifacts/package.json

@@ -0,0 +1,19 @@
+{
+  "name": "cloud-artifacts",
+  "version": "0.0.0",
+  "private": true,
+  "description": "Cloudflare Worker + R2 HTML artifact host (POST /upload → hash URL)",
+  "scripts": {
+    "dev": "wrangler dev",
+    "deploy": "wrangler deploy",
+    "setup": "bash scripts/setup.sh",
+    "cf-typegen": "wrangler types"
+  },
+  "dependencies": {
+    "nanoid": "^5.0.0"
+  },
+  "devDependencies": {
+    "typescript": "^6.0.0",
+    "wrangler": "^4.0.0"
+  }
+}