test(agents): use unittest assertions in example feature tests

[bedus-creation]

Summary

Converts the bare pytest-style assert statements in the example/agents feature tests to proper unittest assertion methods, matching the unittest.IsolatedAsyncioTestCase base they inherit (via tests.test_case.TestCase → HttpTestCase → fastapi_startkit.testing.TestCase).

• assert x == y → self.assertEqual(x, y)
• Async test methods left untouched
• @ChatAgent.fake(...) / @ChatAgent.record(...) decorators left intact

Files

• example/agents/tests/features/test_chat_controller.py
• example/agents/tests/features/test_home_controller.py

Testing

Ran the feature suite against the example app scaffolding — all 3 tests pass:

tests/features/test_chat_controller.py::TestChatController::test_chat_responds_for_basic_greetings PASSED
tests/features/test_chat_controller.py::TestChatController::test_chat_responds_for_other_greetings PASSED
tests/features/test_home_controller.py::TestHomeController::test_home PASSED

Notes

Based on the task/langgraph-agent-harness branch (PR #139). The example app scaffolding and the other_greetings.json record fixture are part of that harness PR and are intentionally not included here — this PR only touches assertion style.