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).

docs/FUNCTIONAL.md

@@ -93,7 +93,7 @@ invitation — so a player still sees and plays existing games of any language.
 
 **Quick game** lets you choose your opponent — an **AI** (the default) or a **random player**.
 With **AI** you start at once against a 🤖 that joins and replies immediately: there is no waiting,
-chat and nudge are off, add-friend is never shown, and the word-check tool still works; instead of a
+there is no chat or nudge — only the word-check tool — add-friend is never shown; instead of a
 per-move clock you lose only after **7 days without a move** (so you can abandon an AI game freely,
 and the AI itself never runs out of time). Choosing a **random player** is auto-match
 (always 2 players), which drops you **straight into the game and you wait inside it**: if it is your turn you
@@ -211,7 +211,9 @@ is awaited at most once per hour (the
 nudge is part of the game chat); both the in-app toast and the out-of-app push (delivered
 via the platform) **name the nudger** ("<opponent>: waiting for your move").
 Chat and the word-check tool share one **comms screen** with **💬 chat** / **🔎 dictionary**
-tabs, reached from the 💬 in the move-history header (with a back to the game). An unread chat
+tabs, reached from the 💬 in the move-history header (with a back to the game). An AI game has no
+chat, so its comms screen is the word-check alone — and once an AI game is finished (no chat, the
+dictionary closed) the 💬 entry disappears entirely. An unread chat
 entry — a message **or a nudge** from an opponent — raises a small **red dot** next to the game
 in the **lobby** and on the game's **score bar**. Opening the **move history** counts as reading
 the chat, even without entering it: the dot clears and the 💬 icon **fade-blinks twice**. A nudge