fix(deck): make done-restore best-effort on move; cover combined states

Round-4 review polish on PR #885:

- The post-move done re-mark is now best-effort: the move PUT has already
  committed by then, so if the /done call (or its re-fetch) fails, log a
  warning with the card's new location and return the moved card instead of
  raising as if the whole move failed. Documented in the docstring.
- Note that duedate is sent explicitly as None (vs update_card omitting it) —
  equivalent for this route.
- Add unit coverage for the swallowed done-restore failure, and an integration
  test for a card that is both done and archived (exercises the done-restore
  re-fetch on an archived card).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/integration/test_deck_move_card_to_board.py

@@ -212,6 +212,46 @@ async def test_move_card_to_board_preserves_archived_status(
     assert after.archived is True, "archived state was lost during the move"
 
 
+async def test_move_card_to_board_preserves_done_and_archived(
+    nc_client: NextcloudClient, two_boards_with_stacks: tuple
+):
+    """A done *and* archived card keeps both states across a cross-board move.
+
+    This exercises the done-restore path (post-move done PUT + re-fetch) on an
+    archived card, confirming get_card on the destination handles it.
+    """
+    source_board_id, source_stack_id, target_board_id, target_stack_id = (
+        two_boards_with_stacks
+    )
+
+    suffix = uuid.uuid4().hex[:8]
+    card = await nc_client.deck.create_card(
+        source_board_id, source_stack_id, f"Done+archived {suffix}"
+    )
+    await nc_client.deck.update_card(
+        board_id=source_board_id,
+        stack_id=source_stack_id,
+        card_id=card.id,
+        done="2030-01-02T03:04:05+00:00",
+    )
+    await nc_client.deck.archive_card(source_board_id, source_stack_id, card.id)
+
+    moved = await nc_client.deck.move_card_to_board(
+        source_board_id=source_board_id,
+        source_stack_id=source_stack_id,
+        card_id=card.id,
+        target_board_id=target_board_id,
+        target_stack_id=target_stack_id,
+    )
+    assert moved.done is not None
+    assert moved.archived is True
+
+    after = await nc_client.deck.get_card(target_board_id, target_stack_id, card.id)
+    assert after.stackId == target_stack_id
+    assert after.done is not None, "done state was lost during the move"
+    assert after.archived is True, "archived state was lost during the move"
+
+
 async def test_move_card_to_board_rejects_stack_not_on_target_board(
     nc_client: NextcloudClient, two_boards_with_stacks: tuple
 ):