fix(example): restore basic evaluation example

Author: dharapandya85

src/agentunit/examples/basic_evaluation.py

@@ -0,0 +1,34 @@
+from agentunit import Evaluation, Task
+
+
+class FakeAdapter:
+    def __init__(self, response: str):
+        self.response = response
+
+    def run(self, prompt: str) -> str:
+        return self.response
+
+
+def main():
+    # define simple task
+    # each task specifies a prompt and expected output
+    task = Task(name="echo-task", prompt="Say hello", expected="hello")
+    # create a fake model adapter that always outputs "hello"
+    fake_model = FakeAdapter(response="hello")
+
+    # build the evaluation
+    evaluation = Evaluation(task=[task], model=fake_model)
+    # results can be inspected/printed
+    results = evaluation.run()
+
+    # print a readable summary
+    print("=== Evaluation Summary ===")
+    for result in results:
+        print(f"Task: {result.task.name}")
+        print(f"Prompt: {result.task.prompt}")
+        print(f"Model Output: {result.output}")
+        print(f"Expected: {result.task.expected}")
+        print(f"Passed: {result.passed}")
+        print("-" * 30)
+    if __name__ == "__main__":
+        main()