refactor(hub): 手搓 agent loop 换成 Vercel AI SDK

将 provider/runner/tools 三件手搓轮子替换为 AI SDK v7 的 generateText + tool:
- 删 openrouter-provider.ts(翻译层消失)、provider.ts 自定义消息类型
- runner.ts 循环体改为 generateText({stopWhen: stepCountIs}),保留 RunRequest/RunResult 公共签名
- tools.ts ToolRegistry 改为 ToolFactory + build(ctx, names?) 按 role 白名单构建 tools record
- workspace/cph/feishu 工具改写为 tool() 定义,execute 闭包捕获 per-run ToolContext
- transcript.ts 改为 ModelMessage[] JSONL(0.0.0 cutover,无迁移)
- server.ts/trigger.ts 接 modelFactory + toolWhitelist
- 测试:helpers 写 MockLanguageModel implements LanguageModelV4;5 个测试改写 + 新增 runner.test.ts
- 移除未使用的 openai 依赖
- ADR-0017 Consequences 同步:loop 委托给 AI SDK,provider seam 是 LanguageModel

tsc 干净,54 tests 全过。

hub/package.json

@@ -7,12 +7,14 @@
     "node": ">=20"
   },
   "dependencies": {
+    "@ai-sdk/openai-compatible": "^3.0.5",
     "@fastify/cookie": "^11.0.2",
     "@larksuiteoapi/node-sdk": "^1.66.1",
     "@prisma/client": "^6.19.3",
+    "ai": "^7.0.16",
     "dotenv": "^17.4.2",
     "fastify": "^5.8.5",
-    "openai": "^4.77.0"
+    "zod": "^4.4.3"
   },
   "devDependencies": {
     "prisma": "^6.19.3",