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/flip.go

@@ -171,8 +171,6 @@ func recordBotDefeat(userID id.UserID, game string) {
 	)
 }
 
-
-
 // redirectToGamesRoom returns the room ID for games-restricted redirect.
 func redirectToGamesRoom(sender id.UserID) string {
 	_ = sender