feat(object): add toHaveOwnProperty method and improve property-path matching in object assertions

ts/namespaces/object.ts

@@ -62,13 +62,21 @@ export class ObjectMatchers<T extends object, M extends TExecutionType> {
     return this.assertion.customAssertion(
       (v) => {
         const obj = v as any;
+        // first check for a literal property (including inherited)
+        if (property in obj) {
+          if (arguments.length === 2) {
+            return plugins.fastDeepEqual(obj[property], value);
+          }
+          return true;
+        }
+        // no direct key, try nested path via dot notation
         const path = property.split('.');
         let current = obj;
         for (const key of path) {
           if (current == null || !(key in current)) {
             return false;
           }
-          current = current[key];
+          current = (current as any)[key];
         }
         if (arguments.length === 2) {
           return plugins.fastDeepEqual(current, value);