fix(offline): give the local human seat the real account id

In a local game the human seat's account id was a synthetic 'local:human:0',
so seatName's `accountId === session.userId` check never matched: the game
header rendered BOTH seats as 🤖 (the vs_ai fallback), and the lobby's
groupGames could not find the viewer's seat, so a human's turn read as
'Their turn' with the hourglass. Carry the real account id on the human seat
(create -> record -> GameView); the robot keeps its synthetic id.

Local games created before this fix keep the old display (no migration).

ui/src/lib/localgame/source.ts

@@ -120,7 +120,7 @@ export class LocalSource implements GameLoopSource {
     const now = nowUnix();
     const record = serializeGame(game, {
       id: opts.id,
-      seats: opts.seats.map((s) => ({ kind: s.kind, name: s.name })),
+      seats: opts.seats.map((s) => ({ kind: s.kind, name: s.name, accountId: s.accountId })),
       createdAtUnix: now,
       updatedAtUnix: now,
       robotLastMoveAtUnix: now,
@@ -341,7 +341,7 @@ export class LocalSource implements GameLoopSource {
     const { game, record } = entry;
     const seats: Seat[] = record.seats.map((s, i) => ({
       seat: i,
-      accountId: `${LOCAL_ID_PREFIX}${s.kind}:${i}`,
+      accountId: s.accountId ?? `${LOCAL_ID_PREFIX}${s.kind}:${i}`,
       displayName: s.name,
       score: game.scoreOf(i),
       hintsUsed: 0,