fix: replace time.sleep with threading.Event in async tests

Address review feedback: use event-based synchronization instead of
time.sleep(0.1) in the two async provider tests to avoid flakiness.

Author: leoromanovsky

tests/test_api.py

@@ -378,38 +378,58 @@ def test_set_provider_and_wait_with_domain():
 
 def test_set_provider_runs_init_in_background():
     """set_provider() should not raise even if initialize() fails."""
+    import threading
+
     # Given
     provider = MagicMock(spec=FeatureProvider)
     provider.initialize.side_effect = Exception("init failed")
+    error_event = threading.Event()
+
+    def handler(_details):
+        error_event.set()
+
+    add_handler(ProviderEvent.PROVIDER_ERROR, handler)
 
     # When - should NOT raise (error is handled in background thread)
     set_provider(provider)
 
-    # Give the background thread a moment to complete
-    import time
-    time.sleep(0.1)
+    # Wait for the background thread to complete and fire the event
+    assert error_event.wait(timeout=1), "PROVIDER_ERROR event not received"
 
     # Then - provider should be in ERROR state (not READY)
     client = get_client()
     assert client.get_provider_status() == ProviderStatus.ERROR
 
+    # Cleanup
+    remove_handler(ProviderEvent.PROVIDER_ERROR, handler)
+
 
 def test_set_provider_async_eventually_becomes_ready():
     """set_provider() runs init in background, provider transitions to READY."""
+    import threading
+
     # Given
     provider = MagicMock(spec=FeatureProvider)
+    ready_event = threading.Event()
+
+    def handler(_details):
+        ready_event.set()
+
+    add_handler(ProviderEvent.PROVIDER_READY, handler)
 
     # When
     set_provider(provider)
 
-    # Give the background thread a moment to complete
-    import time
-    time.sleep(0.1)
+    # Wait for the background thread to complete and fire the event
+    assert ready_event.wait(timeout=1), "PROVIDER_READY event not received"
 
     # Then - provider should be READY
     client = get_client()
     assert client.get_provider_status() == ProviderStatus.READY
 
+    # Cleanup
+    remove_handler(ProviderEvent.PROVIDER_READY, handler)
+
 
 def test_provider_status_is_updated_after_provider_emits_event():
     # Given