pool: a chat /task never reaches the Model Pool judge

[AbirAbbas]

What happened

The Model Pool judge scores tasks when they land (poolJudgeHook in cmd/codeaf/poolrecord.go, wired as taskLanded in cmd/codeaf/chatv3.go). A task started with the chat's ordinary /task never reaches that hook, so its landing is never judged. This was found on 2026-09-25 while fixing the judge's keyless-boot bug in #1519: a hand check of that fix could not reach the judge from /task at all.

Replication

Deterministic: a cmd/codeaf test that lands a /task through the chat's own task road, with a stub worker and the pool in record mode, then checks the pool's judged/ directory, or pool/judge-last.json. Nothing is written today. Compare with the road that does call taskLanded.

By hand (real model, about $0.01):

1. Run /task on a trivial change with CODEAF_MODEL_POOL recording.
2. After it lands, codeaf pool show lists no new judged landing.

The fix

Every road that lands a task, /task included, reports its landing to the judge hook once.

Acceptance

• e2e: after a /task lands, codeaf pool show lists its judged entry.
• Unit: every landing road goes through the one hook. A structural test over the landing sites would do.