fix: silent default test output; verbose controlled by SOURCETEST_VERBOSE env var

go test -json implicitly sets testing.Verbose()=true, so the old guard
always printed manga lists through the script. Switched to an env var
(SOURCETEST_VERBOSE=1) set by the script only when -v is passed.

internal/sourcetest/sourcetest.go

@@ -3,11 +3,14 @@
 package sourcetest
 
 import (
+	"os"
 	"testing"
 
 	"goyomi/internal/source"
 )
 
+var verboseOutput = os.Getenv("SOURCETEST_VERBOSE") == "1"
+
 // Run verifies source metadata and, unless -short is set, calls GetPopularManga
 // and GetLatestUpdates (when supported) against the live site.
 func Run(t *testing.T, s source.CatalogueSource, wantName, wantLang string) {
@@ -39,7 +42,7 @@ func Run(t *testing.T, s source.CatalogueSource, wantName, wantLang string) {
 		if len(page.Mangas) == 0 {
 			t.Fatal("GetPopularManga returned 0 results")
 		}
-		if testing.Verbose() {
+		if verboseOutput {
 			t.Logf("--- GetPopularManga (%d results) ---", len(page.Mangas))
 			for i, m := range page.Mangas {
 				t.Logf("  [%d] %-60s %s", i, m.Title, m.URL)
@@ -67,7 +70,7 @@ func Run(t *testing.T, s source.CatalogueSource, wantName, wantLang string) {
 		if len(page.Mangas) == 0 {
 			t.Fatal("GetLatestUpdates returned 0 results")
 		}
-		if testing.Verbose() {
+		if verboseOutput {
 			t.Logf("--- GetLatestUpdates (%d results) ---", len(page.Mangas))
 			for i, m := range page.Mangas {
 				t.Logf("  [%d] %-60s %s", i, m.Title, m.URL)