games: the table that couldn't end, and the lock that let go too early

A code review of the uno table found the stuck guard had never once fired.
It counted how many bots had passed in a row and wanted more of them than
there are seats — but the bot loop hands the turn back the moment it comes
round to you, so the count could never get there, and your own empty-handed
pass was never in it. A dead table just passed the turn round forever. That
is not an ugly ending, it's a game you cannot finish, and a game you cannot
finish is chips you cannot cash out. So it asks the real question now: is
there anything to draw, and is anyone holding a card that goes.

And the table let go of itself too early. busy came off when the request
landed, not when the script it came back with had finished playing — so for
the seconds a bot lap takes, you could click a card at a board the server
had already moved past. It comes off at the end now, like the other tables.

Also: left: 0 was being dropped on its way out the door, which is the one
number that matters (the seat that just went out), the deck counter didn't
come back after a reshuffle, and hoisting fly() into flyNode() had quietly
flattened the chip arc on every other table in the room.

Claude-Session: https://claude.ai/code/session_013M5nD7PgUboJXoDcYHzpuJ

internal/web/games_uno.go

@@ -124,7 +124,7 @@ type unoEventView struct {
 	Card  *unoCardView `json:"card,omitempty"`
 	Color string       `json:"color,omitempty"`
 	N     int          `json:"n,omitempty"`
-	Left  int          `json:"left,omitempty"`
+	Left  int          `json:"left"` // never omitempty: a seat that goes out leaves zero, and zero is the number the table has to draw
 	Text  string       `json:"text,omitempty"`
 }