fix(task-board): sweep a settled delivery-lane card into the archive, not just Done

[pedrofrxncx]

What: The auto-archive sweep (archive-merged.ts / listItemsAwaitingArchive) still gated on the literal status "done", but shippedLane() sends a delivery-lanes org's shipped cards to "merged"/"post_deploy_validation" instead — they never reach "done" on their own (see packages/shared/src/task-board.ts's shippedLane). The merged-tag sweep hit the exact same gap and was already fixed to gate on the broader TAGGABLE_MERGED_STATUSES/isTaggableMergedStatus set (see the comment on listItemsAwaitingMergedTag), but the archive sweep was left behind on the old literal — so on any org running delivery_lanes_enabled, a shipped card never settles into the archive no matter how old it gets.

Why a maintainer wants this: the archive sweep is the only thing keeping Done from growing unbounded ("a Done column with 77 cards nobody reads" per its own doc comment); for a delivery-lanes org it currently does nothing at all, and nobody would notice until the board is unusable.

Fix: reused the already-established isTaggableMergedStatus (lanes.ts) and TAGGABLE_MERGED_STATUSES (storage/task-board.ts) that tag-merged.ts uses for the identical problem, in both the SQL candidate query and the in-process re-check gate. Also fixed the activity log recording a hardcoded from: "done" on every auto-archive — now records the card's real prior status, which matters once that status can be a delivery lane.

Regression test: inverted the existing integration test "never sweeps a card resting in a delivery lane" (which asserted the bug as intended behavior, with a misleading comment about lane ordering) into "sweeps a settled card resting in a delivery lane, same as Done", mirroring the shape of listItemsAwaitingMergedTag's own coverage.

To verify: bun test apps/api/src/tools/task-board/archive-merged.integration.test.ts (needs the real-Postgres test DB — this worktree has none, so I could not run it locally).

Checked locally: bun test apps/api/src/tools/task-board/archive-merged.test.ts (pure logic, unaffected by this change) passes; tsc --noEmit in apps/api is clean; oxlint on the three touched files is clean; bun run fmt applied. Full CI (including the real-Postgres integration test) validates the rest.

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Summary by cubic

The auto-archive sweep now archives settled cards in delivery lanes, not just cards literally in Done.

• Delivery-lane orgs' shipped cards move to merged/post_deploy_validation and never reach done, so the old gate left them unarchived forever.
• Reuses the existing isTaggableMergedStatus and TAGGABLE_MERGED_STATUSES checks already used by the merged-tag sweep.
• The activity log now records the card's real prior status instead of a hardcoded from: "done".
• Inverts the integration test that previously asserted the buggy behavior.

^{Written for commit bb6b2ec. Summary will update on new commits.}

[pedrofrxncx]

Closing as stale: this PR sat past the bot's 48h merge window, main has moved on, and its CI results no longer reflect the current base. This is a housekeeping close, not a rejection of the change — if the underlying problem still exists, the bot will find it again and open a fresh, rebased PR.

[studio-bot:stale-close]