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/dnd_boss_consumables.go

@@ -90,9 +90,9 @@ func consumeFiredHealingItems(userID id.UserID, fired int) {
 	}
 	// Filter to heal items, sort cheapest-tier-first.
 	type entry struct {
-		id    int64
-		tier  int
-		name  string
+		id   int64
+		tier int
+		name string
 	}
 	var heals []entry
 	for _, item := range items {