feat(ui): vs-AI comms trim, overlay confirm button, recall-to-slot drag

- vs-AI: the comms hub drops the Chat tab (Dictionary only); a finished AI
  game has no comms at all, so its 💬 history-header entry is hidden too.
- Confirm-move ✅: redone as an absolute overlay pinned to the right edge (its
  right edge sits under the preview caption), so the rack keeps a fixed tile
  size — this reverts the tile-shrink that resized the letters at 6 tiles.
- Recall: dragging a placed tile back to the rack now drops it at the slot the
  pointer is over (drag-to-position, a gap opens), instead of snapping to its
  original slot; double-tap still recalls to the origin. New pure recallToSlot.

Tests: placement recallToSlot units; e2e recall-to-position; vs-AI comms e2e
updated. Docs: UI_DESIGN + FUNCTIONAL (+ru).

ui/src/lib/placement.test.ts

@@ -9,6 +9,7 @@ import {
   rackView,
   recallAt,
   recallIndex,
+  recallToSlot,
   reorderIndices,
   reset,
   toSubmit,
@@ -112,3 +113,35 @@ describe('reorderIndices', () => {
     expect(reorderIndices(3, 0, 99)).toEqual([1, 2, 0]); // slot clamped to the end
   });
 });
+
+describe('recallToSlot', () => {
+  it('reinserts the recalled tile at the chosen visible slot, reordering the rack', () => {
+    // Lift Q (slot 1) onto the board, then recall it to visible slot 4.
+    const p = place(newPlacement(rack), 1, 7, 7);
+    const { placement, order } = recallToSlot(p, 7, 7, 4);
+    expect(placement.pending).toHaveLength(0);
+    expect(placement.rack).toEqual(['A', BLANK, 'N', 'I', 'Q', 'W', 'E']);
+    expect(order).toEqual([0, 2, 3, 4, 1, 5, 6]);
+  });
+
+  it('counts only still-visible slots and remaps the remaining pending tiles', () => {
+    // A (slot 0) and N (slot 3) are on the board; recall A to visible slot 2 — the placed N is
+    // skipped, and N's rackIndex follows the rack permutation.
+    let p = place(newPlacement(rack), 0, 7, 7);
+    p = place(p, 3, 7, 8);
+    const { placement, order } = recallToSlot(p, 7, 7, 2);
+    expect(placement.rack).toEqual(['Q', BLANK, 'N', 'A', 'I', 'W', 'E']);
+    expect(order).toEqual([1, 2, 3, 0, 4, 5, 6]);
+    expect(placement.pending).toHaveLength(1);
+    expect(placement.pending[0].rackIndex).toBe(2);
+    expect(placement.rack[placement.pending[0].rackIndex]).toBe('N');
+  });
+
+  it('clamps the slot to the end and is an identity no-op when no tile sits at the cell', () => {
+    const p = place(newPlacement(rack), 1, 7, 7);
+    expect(recallToSlot(p, 7, 7, 99).placement.rack).toEqual(['A', BLANK, 'N', 'I', 'W', 'E', 'Q']);
+    const none = recallToSlot(p, 0, 0, 0);
+    expect(none.placement).toBe(p);
+    expect(none.order).toEqual([0, 1, 2, 3, 4, 5, 6]);
+  });
+});