* fix(terminal): retire explicitly closed pending split connections
* test(memory): keep pending split proof compatible with formatted source
* fix(terminal): confirm pending split retirement before stopping work
* fix(terminal): restore the pending split-close gates CI checks
Three CI gates were red on this branch and all three were this branch's own.
The hook-order parity snapshot did not count the `confirmedCloseRef` this
branch adds to `use-terminal-pane-close-actions.ts`. Dumping the flattened
order against clean `main` shows exactly one added `useRef` at position 148
and no reordering, so the count moves 211 -> 212 and the digest with it.
`pending-split-close-test-fixture.ts` is Vitest support code, but it sits
outside the `*.test` / `*.spec` / `tests` globs that already switch
`anti-slop/no-module-mocking` off, so the gate failed on all twelve of its
`vi.mock` calls. It carries a file-scoped disable with the reason, matching
`work-item-search-test-harness.ts`.
`fix.patch` still described the pre-confirmation shape of the close hook, so
`reproduce.mjs` aborted with `Source changed` and the cited ablation could not
run at this head. Regenerated against the committed sources; the harness again
reports 10 pass / 14 fail before and 24 pass / 0 fail after.
Merges `main` rather than rebasing: #21005 is stacked on this branch.
---------
Co-authored-by: m4air <m4air@Mac.localdomain>
Co-authored-by: Neil <neil@stably.ai>
