feat: honest AI opponent in quick game

New Game's quick game gains an explicit opponent selector — 🤖 AI (default)
or 👤 Random player. AI starts a game seated with a pooled robot that joins
and moves at once: no per-move timeout (a 7-day inactivity loss reusing the
turn-timeout sweeper), chat/nudge disabled, no statistics, the opponent shown
as 🤖 everywhere. The random path (disguised robot) is unchanged.

Driven by one game flag (games.vs_ai), set only on AI-started games so the
disguised path is never revealed; Matchmaker.StartVsAI seats the robot
directly (no open pool); the robot replies event-driven via the game service's
after-commit/after-create hook. Wire: vs_ai on EnqueueRequest + GameView.

PRERELEASE.md

@@ -31,6 +31,7 @@ the edge before prod. Each phase maps back to the owner's raw pre-release TODO l
 | OW | Open auto-match: enter the game at once and wait inside it (robot after 90–180 s) | owner ad-hoc | **done** |
 | DA | Dictionary admin: online release-archive upload → word-diff preview → install/activate; versioned dict volume; active version persisted in DB; resident label = release tag | owner ad-hoc | **done** |
 | AB | Manual account block (admin suspension): permanent/temporary with an editable en+ru reason picklist; a block forfeits the player's active games + cancels their open ones; a backend gate refuses a blocked account with **403 `account_blocked`**; the UI shows a terminal blocked screen and stops all push/poll; manual unblock; temporary blocks self-expire (migration `00003`) | owner ad-hoc | **done** |
+| AI | Honest AI opponent in quick game: an explicit 🤖 AI / 👤 random selector (AI default); the robot is seated and moves at once; 7-day inactivity loss (the per-turn timeout reused); chat/nudge disabled, no statistics; the opponent is shown as 🤖 everywhere | owner ad-hoc | **done** |
 | → | Stage 18 — prod contour deploy | — | see [`PLAN.md`](PLAN.md) |
 
 ## Key findings (these reshaped the raw list — read before starting a phase)
@@ -466,3 +467,39 @@ Then Stage 18.
     `lobby.tournaments` / `lobby.soon`). No backend/wire/history/GCG change.
   - **No schema/wire change → no contour DB wipe.** Bake-back: `docs/UI_DESIGN.md`, `docs/FUNCTIONAL.md`
     (+`_ru`). Regression gate: UI `check` + unit + build + bundle budget + e2e (Chromium & WebKit).
+
+- **AI — Honest AI opponent in quick game** (owner ad-hoc, not on the raw TODO list): a second quick-game
+  opponent the player *knowingly* chooses, distinct from the disguised robot of the random/open path
+  (which is kept as-is). New Game's quick-game mode replaces the "auto-match" subtitle with a two-button
+  selector **🤖 AI / 👤 Random player** (the `.seg`/`.opt` segmented style, AI the default); for AI the
+  move-clock line reads "Loss after 7 days of inactivity" and the "searching" hint is hidden.
+  - **Locked decisions (interview):** AI move is **event-driven** (the robot replies the instant the
+    player's move commits; the 30 s driver is the fallback); AI games **do not touch `account_stats`**
+    (practice, like guests); the **Stage 5 strength logic is reused unchanged** (`playToWin` 40 % from the
+    seed + margin band); **no per-move timeout — a 7-day inactivity loss** instead; the 7-day line lives on
+    the New Game screen (the in-game screen has no move-clock line); chat + nudge **disabled**, word-check
+    kept, add-friend never drawn, opponent shown as **🤖** everywhere.
+  - **The 7-day rule reuses the existing per-turn timeout:** an AI game is created with
+    `turn_timeout_secs = AIInactivityTimeout` (7 days) and the existing timeout sweeper resigns the overdue
+    seat — since the robot moves at once, only the human is ever on the clock, so the per-turn timeout *is*
+    the abandon rule (no new column, no new sweeper).
+  - **One game flag drives everything:** `games.vs_ai` (edited into the R1 baseline — pre-release, so a
+    contour DB wipe after merge). It is set **only** on AI-started games, so a robot-filled random game keeps
+    `vs_ai=false` and the disguised opponent is never revealed; the UI derives 🤖 / the gates **from the flag,
+    never from the opponent account**. New backend path `Matchmaker.StartVsAI` (picks a pooled robot via the
+    existing `Pick`, creates an **active** seated game via `game.Service.Create`, random seat order) — the AI
+    request never enters the open pool, so the open-game reaper never touches it. The robot driver gains a
+    `vs_ai` branch (no sleep, no proactive nudge, zero delay) and a focused `DriveGame`/`TriggerMove` fast
+    path wired from the game service's after-create/after-commit hook (`SetAITrigger`, a func value so the
+    game package never imports the robot package). Chat/nudge gated by a new `social` `VsAI` check
+    (`ErrGameVsAI` → 409 `ai_game`); statistics skipped in `commit` when `vs_ai`.
+  - **Wire:** `EnqueueRequest` += `vs_ai`, `GameView` += `vs_ai` (trailing FB fields, regenerated Go + TS),
+    threaded through the backend DTO, the gateway transcode and the `pkg/wire` + `notify` builders.
+  - **Tests:** `lobby` unit (StartVsAI seats a robot + flags the game; empty pool leaves no game); backend
+    integration (`ai_game_test.go`: active+seated+vs_ai+7-day clock, robot moves immediately, stats skipped,
+    7-day timeout resigns the human, chat/nudge rejected); UI codec round-trip (`vs_ai` on enqueue + game
+    view); e2e (an AI game shows 🤖, no "searching", chat disabled, the dictionary still works) + the
+    existing quick-match e2e updated to pick **Random player** (the default is now AI).
+  - **Schema/wire change → a contour DB wipe** after merge (`DROP SCHEMA backend CASCADE` + restart, the
+    R1/R3 pattern). Bake-back: `docs/ARCHITECTURE.md`, `docs/FUNCTIONAL.md` (+`_ru`), `docs/UI_DESIGN.md`,
+    `backend/README.md`, Go Doc comments.