feat(accountdelete): drop all-robot games + unspoofable [Deleted] label

Q2=B: DropAllRobotGames deletes the deletee's games with no human opponent (vs-AI or
auto-match-robot; children cascade), keeping games with any human seat (anonymized
instead). Q1=A: the anon label is the sentinel [Deleted] — the editable-name rule forbids
brackets, so no live player can impersonate a deleted account. Integration test covers
drop-vs-keep.

backend/internal/accountdelete/delete.go

@@ -25,8 +25,10 @@ import (
 
 // AnonymizedName is the label a deleted account shows to opponents. Display names are
 // stored strings resolved identically for every viewer (no per-viewer localisation in this
-// codebase), so a single canonical label is used.
-const AnonymizedName = "Удалённый игрок"
+// codebase), so a single canonical label is used. The brackets are deliberate: the
+// editable-name rule (account.displayNameRe) forbids them, so a live player can never set a
+// name that impersonates a deleted account.
+const AnonymizedName = "[Deleted]"
 
 // retainDelete is the retained_identities reason written when a credential is journalled
 // because its account is being deleted.
@@ -70,6 +72,38 @@ func (d *Deleter) AnonymizeAndTombstone(ctx context.Context, accountID uuid.UUID
 	})
 }
 
+// dropAllRobotGamesSQL deletes every game in which the account plays and no other seat is a
+// human — a robot seat is one whose account holds a 'robot' identity, so this covers both
+// honest vs-AI games and disguised auto-match substitutes. The game rows are deleted; their
+// moves/chat/players/complaints fall away through ON DELETE CASCADE.
+const dropAllRobotGamesSQL = `
+DELETE FROM games g
+WHERE EXISTS (
+    SELECT 1 FROM game_players p WHERE p.game_id = g.game_id AND p.account_id = $1
+) AND NOT EXISTS (
+    SELECT 1 FROM game_players o
+    WHERE o.game_id = g.game_id AND o.account_id <> $1
+      AND NOT EXISTS (
+          SELECT 1 FROM identities i WHERE i.account_id = o.account_id AND i.kind = 'robot'
+      )
+)`
+
+// DropAllRobotGames deletes the account's games that have no human opponent (solo vs-AI or
+// auto-match-robot games), returning how many were removed. Games with any human seat are
+// kept — their seat is anonymised by AnonymizeAndTombstone instead. Run it after the
+// account's active games are resigned, so no live game is removed under the robot driver.
+func (d *Deleter) DropAllRobotGames(ctx context.Context, accountID uuid.UUID) (int64, error) {
+	res, err := d.db.ExecContext(ctx, dropAllRobotGamesSQL, accountID)
+	if err != nil {
+		return 0, fmt.Errorf("accountdelete: drop all-robot games: %w", err)
+	}
+	n, err := res.RowsAffected()
+	if err != nil {
+		return 0, fmt.Errorf("accountdelete: dropped games count: %w", err)
+	}
+	return n, nil
+}
+
 // journalAndDropIdentities copies the account's live identities into the retention journal
 // (reason=delete) and then removes them, freeing each (kind, external_id) for reuse.
 func journalAndDropIdentities(ctx context.Context, tx *sql.Tx, accountID uuid.UUID, now time.Time) error {