Carries the master sync forward (invariant-companion cleanup, alpha.3 bump);
regenerates the client api catalog so ISession lists both killJob and the new
loadThrough, and refreshes the new ptc-python-turn scenario's system-prompt
pin for this branch's bash timeout-promotion schema text.
The #3289 merge-forward dropped four typescript/no-unnecessary-condition
suppressions from index.ts (boot-write-failure fake child stdin, the
admit()-closure logsTruncated recheck, and both settled rechecks whose
guards flip mid-wait), turning the lint:contracts-ready gate red. Re-add
them with their reasons. The merge also carried a ptc-python-turn session
fixture that was not in canonical packed layout; migrate-packed-session-fixtures
re-writes it so session-fixture-layout passes.
Yichen Jiang