Redraw a copy's originals at the source — the resting layout follows the operation

The modifier flip (⌥ copy / ⌘ move) now reflows the source board once:
a copy re-admits the dragged originals into the resting layout, standing
dimmed in place, and a move lifts them out as before. This retires
DRAG-REORDER.md's operation-blind carve-out and makes 04-interactions.md's
"originals stay" true in flight, not just at echo. The one seam is
DragSession.hiddenMembers reading the observed operation.

Consequences carried honestly: copyCards now takes its index in the
lane's full rendered space (the zones counted the originals, so the
geometry's number is the writer's number — the old neighbour remap is
deleted); resolveOperation freezes under the committed hold exactly as
propose does, fixing a real bug where a settled within-board ⌥-copy drew
the move arrangement until the echo and visibly re-shuffled. Stationary
flips still wait for the next dropUpdated (their own Backlog card).

Claude-Session: https://claude.ai/code/session_01CqjXB7ASoWtbyoGod68k97

Kanban/UI/Board/CardFaceView.swift

@@ -212,10 +212,14 @@ struct CardFaceView: View {
         // genuinely fires on the trash side too: "⌘X works — cut in the trash, paste into a lane is
         // the keyboard-native restore" (04 ▸ The trash, resettled 2026-07-28).
         .cutTreatment(of: card.id, in: store)
-        // The face being dragged out dims the same way while the session is in flight on the trash
-        // side, where the source stays visible: a restore is not a removal until the write lands.
-        // (On the board a dragged card is lifted out of the resting layout entirely, so this never
-        // has anything to act on there — `LaneView.renderedCards`.)
+        // The face being dragged out dims the same way while the session is in flight, wherever the
+        // source stays visible — which is now two places rather than one. On the **trash** side a
+        // restore is not a removal until the write lands, so the row never leaves. On the **board**
+        // side a drag whose effective operation is `.copy` leaves its originals in the resting
+        // layout, because the copy leaves them there (`DragSession.hiddenMembers`), and this is what
+        // marks them as the source of the drag rather than as ordinary neighbours. A `.move`'s
+        // originals are lifted out entirely and this has nothing to act on
+        // (`LaneView.renderedCards`).
         .opacity(drops.session.isDragging(card.id) ? ClipboardTreatment.dimmedOpacity : 1)
         .contentShape(Rectangle())
         // **A card is one flattened accessibility element** (10-accessibility.md ▸ The board through