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/hangman.go

@@ -973,4 +973,3 @@ func (p *HangmanPlugin) recordHangmanScore(userID id.UserID, earned float64) {
 		string(userID), earned, earned,
 	)
 }
-