Add Kaggle mirror + task verifiers (site by @KaKituken, verifiers by reviewer)

[Django-Jiang]

Review: Kaggle mirror (PR #54) — reviewer verifiers + grading contract

Reviewed PR #54, rebased the site onto current main, built the 17-site image
webharbor:kaggle-rebase, ran on alt ports. Kaggle is registered at index 16 (port 40016).

Mechanical checks: PASS

• All 16 sites return 200 (41400-41415)
• Control plane healthy (_health → 17 competitions, 16 datasets, ok)
• Byte-identical reset: md5 = 131cdab6ed840e4e74324ab5bd24dda4 (instance == instance_seed), stable after full task-driving + resets
• POST /reset-all → all sites ready
• Assets pinned to refs/pr/37 (HF discussions/37); fetch_assets.sh succeeds. Maintainer must bump to the merged SHA once the HF PR lands.

Visual / functional depth: PASS (driven via real Playwright form/JS actions, confirmed against the DB)

Login (all 4 benchmark users, TestPass123!); join competition (+ team name); upvote; bookmark;
follow; new discussion; post comment; profile-location edit; dataset download — all persist to SQLite.

Task quality: 1 verifier-side fix, otherwise sound

1. Kaggle--11 was pre-satisfied by the seed (fixed in the verifier). seed_discussions already
   seeds one davidtran comment on the titanic-feature-ideas thread, so an existence check
   couldn't confirm the agent's new comment. The verifier now uses a delta (davidtran comment
   count on that thread must increase vs the seed). No task-text change needed.

Minor (non-blocking): Kaggle--0 ("Titanic passenger survival") — two Getting-Started Titanic
competitions exist (titanic-survival, spaceship-titanic-rescue), but both use metric
"Classification Accuracy", so the answer is unambiguous; the verifier requires navigating the
titanic-survival page. Several read-only answers (accuracy, ROC AUC, Apache 2.0, CC0, 7 lessons)
are frontier-LLM-guessable; the anti-shortcut nav gate (must open the specific competition/model/
course/dataset page) mitigates this, and site-specific tasks (team names, host schedules,
carolwong's notebook, rankings) anchor the harder ones.

Rebased onto current main in this PR

PR #54 branched from a 16-site main and registered kaggle at index 15 (a slot now taken by
merriam_webster). This reviewer PR rebases the site onto current main:

• kaggle re-registered as index 16 / port 40016 in websyn_start.sh, control_server.py, and
  Dockerfile (EXPOSE 40000-40016).
• .assets-revision pinned to refs/pr/37 (HF discussions/37), which contains all 16 current-main
  site tarballs plus kaggle.tar.gz — so this PR builds end-to-end. Maintainer: after HF discussions/37
  is rebased onto HF main and merged, bump .assets-revision to the merged SHA.
• The full 17-site image builds; all 17 sites return 200; kaggle serves at 40016; byte-identical reset
  holds; the verifiers were re-confirmed against the rebased container (read-only PASS, no-op FAIL,
  and a stateful drive+PASS at the new port). The current-main agent_demo provides the
  eval_judge --verifier True PRIMARY-grader path.

Grading contract authored (reviewer)

• sites/kaggle/verify/verify_lib.py (shared deterministic + anchored-LLM utilities) + 20 per-task
  verifiers verify_0.py … verify_19.py.
• tasks.jsonl backfilled with verifier_path + judge_rubric per row; no answer key.
• Deterministic-first: navigation evidence (anti knowledge-shortcut) + on-page answer match +
  SQLite after-state (competition_entries, votes, bookmarks, follows, discussions/comments, download
  counter, user profile). LLM/screenshot checks anchored on ground truth and SKIP when the LLM is
  unavailable.

Grading validation (verifiers run standalone against the live container DB)

• No-op (homepage only, empty answer, DB = seed): all 20 verifiers FAIL. Zero false positives.
• Genuine completion (real form/JS-driven actions + correct read-only answers): all 20 PASS.
• Wrong answer (read-only naming the wrong metric/license/user/team): FAIL.
• Shortcut (correct answer, no detail-page nav): FAIL on the nav gate.
• State-mismatch (correct nav, DB reverted to seed): FAIL on the DB gate.
• Byte-identical reset holds after the full drive (md5 unchanged).

Verdict

Grading contract is ready and validated; the site is rebased onto current main (kaggle at index
16 / port 40016) and builds from refs/pr/37. Ready to merge once the maintainer bumps
.assets-revision to the merged HF SHA after HF discussions/37 lands on HF main.

[TabsPhasers]

后续 Review PR 已创建：#106（https://github.com/aiming-lab/WebHarbor/pull/106）。

该 PR 保留 @KaKituken 的站点贡献（#54）并延续本 PR 的 verifier/rubric 工作，基于当前 main（3600493）接管，Kaggle 注册为 index 23 / 端口 40024。剩余 blocker：HF ChilleD/WebHarbor #74 合并后 pin .assets-revision 到 merge SHA 并 clean-fetch 复验。当前为 Draft，未满足合并条件。后续 Review 请转到 #106。