gofmt: bring internal/ and cmd/ back to gofmt -l clean

Mechanical `gofmt -w ./internal ./cmd`. Mostly struct-field realignment that
had drifted, plus a few trailing-newline fixes. No behaviour change — gofmt is
semantics-preserving, and build/vet/test are green either side.

Split out from the code-review fixes that follow so those stay reviewable
instead of hiding inside a wall of realignment.

internal/plugin/holdem.go

@@ -1249,7 +1249,6 @@ func (p *HoldemPlugin) removePlayer(game *HoldemGame, uid id.UserID) {
 	}
 }
 
-
 func (p *HoldemPlugin) getNPCBalance() int64 {
 	d := db.Get()
 	var balance int64