Python: [BREAKING] Python: Provider-leading client design & OpenAI package extraction (#4818)

* Python: Provider-leading client design & OpenAI package extraction

Major refactoring of the Python Agent Framework client architecture:

- Extract OpenAI clients into new `agent-framework-openai` package
- Core package no longer depends on openai, azure-identity, azure-ai-projects
- Rename clients for discoverability: OpenAIResponsesClient → OpenAIChatClient,
  OpenAIChatClient → OpenAIChatCompletionClient
- Unify `model_id`/`deployment_name`/`model_deployment_name` → `model` param
- New FoundryChatClient for Azure AI Foundry Responses API
- New FoundryAgent/FoundryAgentClient for connecting to pre-configured Foundry agents
- Remove OpenAIBase/OpenAIConfigMixin from non-deprecated client MRO
- Deprecate AzureOpenAI* clients, AzureAIClient, OpenAIAssistantsClient
- Reorganize samples: azure_openai+azure_ai+azure_ai_agent → azure/
- ADR-0020: Provider-Leading Client Design

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix: missing Agent imports in samples, .model_id → .model in foundry_local sample

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix: CI failures — mypy errors, coverage targets, sample imports

- azure-ai mypy: add type ignores for TypedDict total=, model arg, forward ref
- Coverage: replace core.azure/openai targets with openai package target
- project_provider: add type annotation for opts dict

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix: populate openai .pyi stub, fix broken README links, coverage targets

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fixes

* updated observabilitty

* reset azure init.pyi

* fix errors

* updated adr number

* fix foundry local

* fixed not renamed docstrings and comments, and added deprecated markers to old classes

* fix tests and pyprojects

* fix test vars

* updated function tests

* update durable

* updated test setup for functions

* Fix Foundry auth in workflow samples

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Stabilize Python integration workflows

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Update hosting samples for Foundry

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Trigger full CI rerun

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Trigger CI rerun again

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* trigger rerun

* trigger rerun

* fix for litellm

* undo durabletask changes

* Move Foundry APIs into foundry namespace

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Fix Foundry pyproject formatting

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Split provider samples by Foundry surface

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Restore hosting sample requirements

Also fix the Foundry Local sample link after the provider sample move.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* updated tests

* udpated foundry integration tests

* removed dist from azurefunctions tests

* Use separate Foundry clients for concurrent agents

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix client setup in azfunc and durable

* disabled two tests

* updated setup for some function and durable tests

* improved azure openai setup with new clients

* ignore deprecated

* fixes

* skip 11

* remove openai assistants int tests

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

python/samples/semantic-kernel-migration/orchestrations/sequential.py

@@ -15,12 +15,13 @@ import asyncio
 from collections.abc import Sequence
 from typing import cast
 
-from agent_framework import Message
+from agent_framework import Agent, Message
 from agent_framework.azure import AzureOpenAIChatClient
 from agent_framework.orchestrations import SequentialBuilder
 from azure.identity import AzureCliCredential
 from dotenv import load_dotenv
-from semantic_kernel.agents import Agent, ChatCompletionAgent, SequentialOrchestration
+from semantic_kernel.agents import Agent as SKAgent
+from semantic_kernel.agents import ChatCompletionAgent, SequentialOrchestration
 from semantic_kernel.agents.runtime import InProcessRuntime
 from semantic_kernel.connectors.ai.open_ai import AzureChatCompletion
 from semantic_kernel.contents import ChatMessageContent
@@ -36,7 +37,7 @@ PROMPT = "Write a tagline for a budget-friendly eBike."
 ######################################################################
 
 
-def build_semantic_kernel_agents() -> list[Agent]:
+def build_semantic_kernel_agents() -> list[SKAgent]:
     credential = AzureCliCredential()
 
     writer_agent = ChatCompletionAgent(
@@ -77,12 +78,12 @@ async def sk_agent_response_callback(
 async def run_agent_framework_example(prompt: str) -> list[Message]:
     client = AzureOpenAIChatClient(credential=AzureCliCredential())
 
-    writer = client.as_agent(
+    writer = Agent(client=client,
         instructions=("You are a concise copywriter. Provide a single, punchy marketing sentence based on the prompt."),
         name="writer",
     )
 
-    reviewer = client.as_agent(
+    reviewer = Agent(client=client,
         instructions=("You are a thoughtful reviewer. Give brief feedback on the previous assistant message."),
         name="reviewer",
     )