Python: [BREAKING] Simplify API: ChatAgent -> Agent, ChatMessage -> Message (#3747)

* [BREAKING] Rename ChatAgent -> Agent, ChatMessage -> Message, ChatClientProtocol -> SupportsChatGetResponse

Simplify the public API by removing redundant 'Chat' prefix from core types:
- ChatAgent -> Agent
- RawChatAgent -> RawAgent
- ChatMessage -> Message
- ChatClientProtocol -> SupportsChatGetResponse

Also renamed internal WorkflowMessage (was Message in _runner_context) to avoid collision.

No backward compatibility aliases - this is a clean breaking change.

* [BREAKING] Rename Agent chat_client parameter to client

* Fix rebase issues: WorkflowMessage references and broken markdown links

* Fix formatting and lint issues from code quality checks

* Fix import ordering in workflow sample files

* fixed rebase

* Fix test failures: use WorkflowMessage and A2AMessage after ChatMessage→Message rename

- Replace Message(data=..., source_id=...) with WorkflowMessage(...) in workflow tests
- Fix isinstance check in A2A agent to use A2AMessage instead of Message
- Fix import in test_workflow_observability.py (Message→WorkflowMessage)

* Fix lint, fmt, and sample errors after ChatMessage→Message rename

- Auto-fix 70+ ruff lint issues across samples (ChatMessage→Message refs)
- Fix HostedVectorStoreContent→Content.from_hosted_vector_store in file search sample
- Fix _normalize_messages→normalize_messages in custom agent sample
- Fix context.terminate→raise MiddlewareTermination in middleware samples
- Fix with_update_hook→with_transform_hook in override middleware sample
- Add TOptions_co import back to custom_chat_client sample
- Add noqa for FastAPI File() default in chatkit sample
- Fix B023 loop variable capture in weather agent sample

* fix: update Agent constructor calls from chat_client to client in declaration-only tool tests

* fix: add register_cleanup to devui lazy-loading proxy and type stub

* fixed tests and updated new pieces

* fix agui typevar

* fix merge errors

* fix merge conflicts

* fiux merge

* Remove unused links

---------

Co-authored-by: Evan Mattson <evan.mattson@microsoft.com>

python/packages/bedrock/agent_framework_bedrock/_chat_client.py

@@ -14,7 +14,6 @@ from agent_framework import (
     AGENT_FRAMEWORK_USER_AGENT,
     BaseChatClient,
     ChatAndFunctionMiddlewareTypes,
-    ChatMessage,
     ChatMiddlewareLayer,
     ChatOptions,
     ChatResponse,
@@ -24,6 +23,7 @@ from agent_framework import (
     FunctionInvocationConfiguration,
     FunctionInvocationLayer,
     FunctionTool,
+    Message,
     ResponseStream,
     ToolProtocol,
     UsageDetails,
@@ -325,7 +325,7 @@ class BedrockChatClient(
     def _inner_get_response(
         self,
         *,
-        messages: Sequence[ChatMessage],
+        messages: Sequence[Message],
         options: Mapping[str, Any],
         stream: bool = False,
         **kwargs: Any,
@@ -359,7 +359,7 @@ class BedrockChatClient(
 
     def _prepare_options(
         self,
-        messages: Sequence[ChatMessage],
+        messages: Sequence[Message],
         options: Mapping[str, Any],
         **kwargs: Any,
     ) -> dict[str, Any]:
@@ -410,7 +410,7 @@ class BedrockChatClient(
         return run_options
 
     def _prepare_bedrock_messages(
-        self, messages: Sequence[ChatMessage]
+        self, messages: Sequence[Message]
     ) -> tuple[list[dict[str, str]], list[dict[str, Any]]]:
         prompts: list[dict[str, str]] = []
         conversation: list[dict[str, Any]] = []
@@ -482,7 +482,7 @@ class BedrockChatClient(
 
         return aligned_blocks
 
-    def _convert_message_to_content_blocks(self, message: ChatMessage) -> list[dict[str, Any]]:
+    def _convert_message_to_content_blocks(self, message: Message) -> list[dict[str, Any]]:
         blocks: list[dict[str, Any]] = []
         for content in message.contents:
             block = self._convert_content_to_bedrock_block(content)
@@ -593,7 +593,7 @@ class BedrockChatClient(
         message = output.get("message", {})
         content_blocks = message.get("content", []) or []
         contents = self._parse_message_contents(content_blocks)
-        chat_message = ChatMessage(role="assistant", contents=contents, raw_representation=message)
+        chat_message = Message(role="assistant", contents=contents, raw_representation=message)
         usage_details = self._parse_usage(response.get("usage") or output.get("usage"))
         finish_reason = self._map_finish_reason(output.get("completionReason") or response.get("stopReason"))
         response_id = response.get("responseId") or message.get("id")