chore: fix pre-existing lint issues blocking commits

- wsl_v5: blank line before t.Fatal after rows.Close
- staticcheck SA5011: explicit return after t.Fatal for nil guards

No behavior change.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/database/search_test.go

@@ -575,6 +575,8 @@ func TestSearchFTSTracks(t *testing.T) {
 
 	if br == nil {
 		t.Fatal("SearchFTSTracks: Bohemian Rhapsody not found")
+
+		return
 	}
 
 	// Verify all fields are populated.