feat(sites): 站点请求失败留样(site_failure_sample,每站最近 5 份)

- 迁移 0077 新表 site_failure_sample:类型(parse_error / challenge)、请求类型、脱敏 URL、状态码、
  关键响应头、错误文案、命中规则、脱敏页面开头(≤ 64 KB);样本几十 KB,不放进每条请求都读的 site.config
- 适配器 onFailureSample 回调接到 runtime.siteAdapter,异步写入并删到最近 5 份,写失败只记日志
- GET /sites/{id}/failure-samples(不带正文)与 /failure-samples/{sampleId}(带正文)

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01Cxwgnn2pbzQ7rXv3rq7fei

packages/contracts/src/sources.ts

@@ -701,6 +701,35 @@ export const SiteSnapshot = EntityBase.extend({
 });
 export type SiteSnapshot = z.infer<typeof SiteSnapshot>;
 
+/** 失败留样的类型:页面结构无法识别 / 人机验证 */
+export const SiteFailureSampleKind = z.enum(["parse_error", "challenge"]);
+export type SiteFailureSampleKind = z.infer<typeof SiteFailureSampleKind>;
+
+/**
+ * 站点请求失败留样(列表 / 搜索 / 详情报 parse_error / challenge 时存的脱敏页面开头,每站最近 5 份)。
+ * requestKind:search / list / detail / health / other;headers 只有 server、cf-mitigated、cf-ray、content-type。
+ */
+export const SiteFailureSample = z.object({
+  id: Id,
+  siteId: Id,
+  kind: SiteFailureSampleKind,
+  requestKind: z.string(),
+  /** 已脱敏 */
+  url: z.string(),
+  httpStatus: z.number().int().nullable(),
+  headers: z.record(z.string(), z.string()),
+  message: z.string(),
+  rule: z.string().nullable(),
+  /** 脱敏后的页面开头(≤ 64 KB) */
+  body: z.string(),
+  truncated: z.boolean(),
+  createdAt: Timestamp,
+});
+export type SiteFailureSample = z.infer<typeof SiteFailureSample>;
+/** 列表里不带页面正文,只给字节数 */
+export const SiteFailureSampleSummary = SiteFailureSample.omit({ body: true }).extend({ bodyBytes: NonNegInt });
+export type SiteFailureSampleSummary = z.infer<typeof SiteFailureSampleSummary>;
+
 /** 站点访问默认(站点定义 umt.defaults 与 settings.sites 合并后,取更保守的一方) */
 export const SiteAccessDefaults = z.object({
   snapshotIntervalSec: z.number().int(),