Remove the "halves" cover style again

Tried in macOS Terminal: it does not look good there either.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019reK4DUGYqDUjniWYJvwUW

internal/config/config_test.go

@@ -100,7 +100,7 @@ func TestShowCovers(t *testing.T) {
 
 func TestCoverStyleValidation(t *testing.T) {
 	base := `{"radarr":{"url":"http://r","apikey":"k"},"sonarr":{"url":"http://s","apikey":"k"},"sabnzbd":{"url":"http://a","apikey":"k"},"ui":{"cover_style":`
-	for _, ok := range []string{`"auto"`, `"quadrant"`, `"sextant"`, `"cells"`, `"halves"`, `"kitty"`, `""`} {
+	for _, ok := range []string{`"auto"`, `"quadrant"`, `"sextant"`, `"cells"`, `"kitty"`, `""`} {
 		if _, err := Parse([]byte(base + ok + `}}`)); err != nil {
 			t.Errorf("%s rejected: %v", ok, err)
 		}