everything: trigger-elicitation-request-async polls past the 10-minute TTL it requests #4986

Problem

trigger-elicitation-request-async creates its client task with a 10-minute TTL, then polls up to 600 times one second apart. With polling overhead that outlasts the TTL, so a client that honors the TTL expires the task and the tool fails on its last poll.

Where it is pinned

src/everything/__tests__/tasks.test.ts: "fails on the last poll instead when the client honors the 10-minute TTL", added in #4978 (Wave 1 of #4857). Each of these tests carries a KNOWN BUG marker: it asserts the current, wrong behavior, so the fix has to change it.

Expected

The polling budget fits inside the TTL the tool requested (or the TTL covers the polling window).

Done when

• The behavior above is fixed, in the legacy-era (2025-11-25) server on SDK 1.x.
• The pinning tests assert the correct behavior, and their KNOWN BUG markers are gone.
• The per-file 90% coverage gate still passes.