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_abilities_test.go

@@ -54,9 +54,9 @@ func TestActiveAbilityCatalogue(t *testing.T) {
 
 func TestParseAbility(t *testing.T) {
 	cases := []struct {
-		in   string
-		id   string
-		ok   bool
+		in string
+		id string
+		ok bool
 	}{
 		{"second_wind", "second_wind", true},
 		{"second wind", "second_wind", true},