Fail closed when call-graph heuristic lacks class info

Tighten CallGraphPathFinder heuristic matching to avoid cross-class linking when only method names are available and class ownership is unknown.

Co-authored-by: Cursor <cursoragent@cursor.com>

state_machine_exporter/src/main/java/click/kamil/springstatemachineexporter/analysis/service/CallGraphPathFinder.java

@@ -389,7 +389,9 @@ public class CallGraphPathFinder {
             return false;
         }
 
-        return true;
+        // If we have no class ownership information for either side, we can't prove a match beyond the
+        // method name. Fail closed to avoid accidental cross-class linking.
+        return false;
     }
 
     private boolean isFullyQualifiedMethod(String methodFqn) {