fix(adapters): 识别 200 状态的挑战 / 人机验证页,解析失败前兜底,失败页面留样

- detectChallenge 支持页面类请求(GET + Accept text/html)的 2xx 响应:正文只先读 256 KB,
  短页且没有种子表 / 用户信息块时,认 Cloudflare 挑战标题 / 脚本与 Turnstile / hCaptcha / reCAPTCHA 门页;
  带登录表单的页面不算门页。非页面请求不读正文
- siteFetch 用上面的判定;挑战错误附脱敏页面样本,文案带级联结果(x-umt-challenge)
- spider 适配器:认不出列表 / 详情时先看是不是人机验证页,是就报 challenge(「搜索页需要人机验证」),
  不再报改版;parse_error / challenge 都经 deps.onFailureSample 交出脱敏样本(前 64 KB,去掉个人信息块、
  passkey / authkey / uid / 用户名 / Cookie / 邮箱)
- classifyChallengePage 也认门页(浏览器过挑战时不再把门页当已通过)

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

packages/adapters/src/sites/index.ts

@@ -1,10 +1,17 @@
 export {
+  CHALLENGE_OUTCOME_HEADER,
+  CHALLENGE_PEEK_BYTES,
   CHALLENGE_STATUSES,
   type ChallengePageKind,
+  challengeGateRule,
+  challengeOutcomeText,
   challengeRuleOfHeaders,
   challengeRuleOfHtml,
+  challengeRuleOfOkPage,
+  challengeRuleOfUnrecognizedPage,
   classifyChallengePage,
   detectChallenge,
+  isPageRequest,
 } from "./challenge.ts";
 export {
   audiencesDefinition,
@@ -34,6 +41,13 @@ export {
   structureDescription,
 } from "./detail-description.ts";
 export { type FormattedDetailPage, formatDetailPage } from "./detail-format.ts";
+export {
+  buildFailureSample,
+  FAILURE_SAMPLE_MAX_BYTES,
+  redactPageHtml,
+  type SiteFailureSample,
+  type SiteRequestKind,
+} from "./failure-sample.ts";
 export {
   type FeedMediaType,
   normalizeSiteFeedItem,