test: Add comprehensive test coverage (Phase 4)

- Added tests for new TypedDict definitions
  - test_api_responses.py: Tests for all API response types
  - test_callback_types.py: Tests for callback data structures
  - Validates field types, optional fields, and real-world usage

- Added tests for TaskManagerMixin
  - test_task_management_proper.py: Comprehensive async task management tests
  - Tests task creation, cleanup, error handling, and concurrency
  - Validates persistent tasks and memory management

- Fixed existing test issues
  - Fixed test_market_data.py to use correct field names
  - Tests now check 'name' field instead of 'symbol' for contract matching

Added 47 new tests covering critical functionality from previous phases.
This significantly improves test coverage for type safety and async
task management features.

Author: TexasCoding

tests/client/test_market_data.py

@@ -206,29 +206,29 @@ async def test_select_best_contract(self, mock_httpx_client):
                 with pytest.raises(ProjectXInstrumentError):
                     client._select_best_contract([], "MGC")
 
-                # Test with exact match
+                # Test with exact match (uses 'name' field, not 'symbol')
                 contracts = [
-                    {"symbol": "ES", "name": "E-mini S&P 500"},
-                    {"symbol": "MGC", "name": "Micro Gold"},
-                    {"symbol": "MNQ", "name": "Micro Nasdaq"},
+                    {"symbol": "ES", "name": "ES"},
+                    {"symbol": "MGC", "name": "MGC"},
+                    {"symbol": "MNQ", "name": "MNQ"},
                 ]
 
                 result = client._select_best_contract(contracts, "MGC")
-                assert result["symbol"] == "MGC"
+                assert result["name"] == "MGC"
 
                 # Test with futures contracts
                 futures_contracts = [
-                    {"symbol": "MGC", "name": "Micro Gold Front Month"},
-                    {"symbol": "MGCM23", "name": "Micro Gold June 2023"},
-                    {"symbol": "MGCZ23", "name": "Micro Gold December 2023"},
+                    {"symbol": "MGC", "name": "MGC"},
+                    {"symbol": "MGCM23", "name": "MGCM23"},
+                    {"symbol": "MGCZ23", "name": "MGCZ23"},
                 ]
 
                 result = client._select_best_contract(futures_contracts, "MGC")
-                assert result["symbol"] == "MGC"
+                assert result["name"] == "MGC"
 
                 # When no exact match, should pick first one
                 result = client._select_best_contract(contracts, "unknown")
-                assert result["symbol"] == "ES"
+                assert result["name"] == "ES"
 
     @pytest.mark.asyncio
     async def test_get_bars(