style: apply gofmt across Go sources

Repo-wide gofmt sweep: const-block alignment, doc-comment spacing,
statement-after-brace fix in media.go, trailing blank lines. No
semantic changes — whitespace-insensitive diff is empty for every
file in this commit.

cmd/server/tests/collections_preview_test.go

@@ -382,7 +382,7 @@ func createPreviewTestMediaItems(t *testing.T, db *database.Queries, libraryID s
 		media, err := db.CreateMediaItem(ctx, database.CreateMediaItemParams{
 			LibraryID: pgtype.UUID{Bytes: libUUID, Valid: true},
 			Title:     "Preview Test Book " + string(rune('A'+i)),
-			Authors:  []string{"Test Author " + string(rune('A'+i))},
+			Authors:   []string{"Test Author " + string(rune('A'+i))},
 			Genre:     pgtype.Text{String: genre, Valid: true},
 			FilePath:  "/tmp/test" + string(rune('A'+i)) + ".epub",
 			FileSize:  pgtype.Int8{Int64: 1024, Valid: true},