Why: the three cards whose PRs are merged (Backend #212, #226, #237) were
still sitting at .task/ top level, which keeps the main checkout reporting
card debt. Only the status line and the merge fact were added; the historical
record inside each card is untouched.
Evidence: Gitea API for PRs 212/226/237 all report state=closed merged=true
(merge commits 56a7f9f440, 508288fbed, f084d10aa5); triage receipt
/tmp/be-triage-cardclose-20261021.json (verdict NEW).
Impact: .task bookkeeping only; no code change, no submodule pin change.
Refs: fix/close-merged-task-cards
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