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/e2e/game.spec.ts

@@ -284,6 +284,28 @@ test('a placed tile drags from one board cell to another (relocation)', async ({
   expect(to).not.toBe(from);
 });
 
+test('a placed tile drags back to a chosen rack slot (recall-to-position)', async ({ page }) => {
+  await openGame(page);
+  // Place the first rack tile (slot 0) on the board, remembering its letter.
+  await page.locator('.rack .tile').first().click();
+  const placed = (await page.locator('.rack .tile .letter').first().textContent()) ?? '';
+  await page.locator('[data-cell]:not(.filled)').nth(30).click();
+  const pending = page.locator('[data-cell].pending');
+  await expect(pending).toHaveCount(1);
+
+  // Drag it from the board back onto a later rack slot (the 4th visible tile), not its origin.
+  const fb = await pending.first().boundingBox();
+  const slot = await page.locator('[data-rack] .tile').nth(3).boundingBox();
+  await page.mouse.move(fb!.x + fb!.width / 2, fb!.y + fb!.height / 2);
+  await page.mouse.down();
+  await page.mouse.move(slot!.x + 2, slot!.y + slot!.height / 2, { steps: 10 });
+  await page.mouse.up();
+
+  // Recalled (no pending) and reinserted at the drop slot — slot 3, not its origin slot 0.
+  await expect(pending).toHaveCount(0);
+  await expect(page.locator('[data-rack] .tile .letter').nth(3)).toHaveText(placed);
+});
+
 test('comms hub: chat and dictionary share a screen, back returns to the game', async ({ page }) => {
   await openGame(page);
   await page.locator('.scoreboard').click(); // open the history