Python: [BREAKING] Types API Review improvements (#3647)

* Replace Role and FinishReason classes with NewType + Literal

- Remove EnumLike metaclass from _types.py
- Replace Role class with NewType('Role', str) + RoleLiteral
- Replace FinishReason class with NewType('FinishReason', str) + FinishReasonLiteral
- Update all usages across codebase to use string literals
- Remove .value access patterns (direct string comparison now works)
- Add backward compatibility for legacy dict serialization format
- Update tests to reflect new string-based types

Addresses #3591, #3615

* Simplify ChatResponse and AgentResponse type hints (#3592)

- Remove overloads from ChatResponse.__init__
- Remove text parameter from ChatResponse.__init__
- Remove | dict[str, Any] from finish_reason and usage_details params
- Remove **kwargs from AgentResponse.__init__
- Both now accept ChatMessage | Sequence[ChatMessage] | None for messages
- Update docstrings and examples to reflect changes
- Fix tests that were using removed kwargs
- Fix Role type hint usage in ag-ui utils

* Remove text parameter from ChatResponseUpdate and AgentResponseUpdate (#3597)

- Remove text parameter from ChatResponseUpdate.__init__
- Remove text parameter from AgentResponseUpdate.__init__
- Remove **kwargs from both update classes
- Simplify contents parameter type to Sequence[Content] | None
- Update all usages to use contents=[Content.from_text(...)] pattern
- Fix imports in test files
- Update docstrings and examples

* Rename from_chat_response_updates to from_updates (#3593)

- ChatResponse.from_chat_response_updates → ChatResponse.from_updates
- ChatResponse.from_chat_response_generator → ChatResponse.from_update_generator
- AgentResponse.from_agent_run_response_updates → AgentResponse.from_updates

* Remove try_parse_value method from ChatResponse and AgentResponse (#3595)

- Remove try_parse_value method from ChatResponse
- Remove try_parse_value method from AgentResponse
- Remove try_parse_value calls from from_updates and from_update_generator methods
- Update samples to use try/except with response.value instead
- Update tests to use response.value pattern
- Users should now use response.value with try/except for safe parsing

* Add agent_id to AgentResponse and clarify author_name documentation (#3596)

- Add agent_id parameter to AgentResponse class
- Document that author_name is on ChatMessage objects, not responses
- Update ChatResponse docstring with author_name note
- Update AgentResponse docstring with author_name note

* Simplify ChatMessage.__init__ signature (#3618)

- Make contents a positional argument accepting Sequence[Content | str]
- Auto-convert strings in contents to TextContent
- Remove overloads, keep text kwarg for backward compatibility with serialization
- Update _parse_content_list to handle string items
- Update all usages across codebase to use new format: ChatMessage("role", ["text"])

* Allow Content as input on run and get_response

- Update prepare_messages and normalize_messages to accept Content
- Update type signatures in _agents.py and _clients.py
- Add tests for Content input handling

* Fix ChatMessage usage across packages and samples

Update all remaining ChatMessage(role=..., text=...) to use new
ChatMessage('role', ['text']) signature.

* Fix Role string usage and response format parsing

- Fix redis provider: remove .value access on string literals
- Fix durabletask ensure_response_format: set _response_format before accessing .value

* Fix ollama .value and ai_model_id issues, handle None in content list

- Fix ollama _chat_client: remove .value on string literals
- Fix ollama _chat_client: rename ai_model_id to model_id
- Fix _parse_content_list: skip None values gracefully

* Fix A2AAgent type signature to include Content

* Fix Role/FinishReason NewType dict annotations and improve test coverage to 95%

* Fix mypy errors for Role/FinishReason NewType usage

* Fix Role.TOOL and Role.ASSISTANT usage in _orchestrator_helpers.py

* Fix Role NewType usage in durabletask _models.py

python/packages/durabletask/tests/test_executors.py

@@ -11,7 +11,7 @@ from typing import Any
 from unittest.mock import Mock
 
 import pytest
-from agent_framework import AgentResponse, Role
+from agent_framework import AgentResponse
 from durabletask.entities import EntityInstanceId
 from durabletask.task import Task
 from pydantic import BaseModel
@@ -241,7 +241,7 @@ class TestClientAgentExecutorFireAndForget:
         # Verify it contains an acceptance message
         assert isinstance(result, AgentResponse)
         assert len(result.messages) == 1
-        assert result.messages[0].role == Role.SYSTEM
+        assert result.messages[0].role == "system"
         # Check message contains key information
         message_text = result.messages[0].text
         assert "accepted" in message_text.lower()
@@ -294,7 +294,7 @@ class TestOrchestrationAgentExecutorFireAndForget:
         response = result.get_result()
         assert isinstance(response, AgentResponse)
         assert len(response.messages) == 1
-        assert response.messages[0].role == Role.SYSTEM
+        assert response.messages[0].role == "system"
         assert "test-789" in response.messages[0].text
 
     def test_orchestration_blocking_mode_calls_call_entity(self, mock_orchestration_context: Mock) -> None:
@@ -392,7 +392,7 @@ class TestDurableAgentTask:
         result = task.get_result()
         assert isinstance(result, AgentResponse)
         assert len(result.messages) == 1
-        assert result.messages[0].role == Role.ASSISTANT
+        assert result.messages[0].role == "assistant"
 
     def test_durable_agent_task_propagates_failure(self, configure_failed_entity_task: Any) -> None:
         """Verify DurableAgentTask propagates task failures."""
@@ -519,8 +519,8 @@ class TestDurableAgentTask:
         result = task.get_result()
         assert isinstance(result, AgentResponse)
         assert len(result.messages) == 2
-        assert result.messages[0].role == Role.ASSISTANT
-        assert result.messages[1].role == Role.ASSISTANT
+        assert result.messages[0].role == "assistant"
+        assert result.messages[1].role == "assistant"
 
     def test_durable_agent_task_is_not_complete_initially(self, mock_entity_task: Mock) -> None:
         """Verify DurableAgentTask is not complete when first created."""