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/04-hosting/azure_functions/README.md

@@ -11,7 +11,7 @@ All of these samples are set up to run in Azure Functions. Azure Functions has a
 
 - Install [Azurite storage emulator](https://learn.microsoft.com/en-us/azure/storage/common/storage-install-azurite?toc=%2Fazure%2Fstorage%2Fblobs%2Ftoc.json&bc=%2Fazure%2Fstorage%2Fblobs%2Fbreadcrumb%2Ftoc.json&tabs=visual-studio%2Cblob-storage)
 
-- Create an [Azure OpenAI](https://azure.microsoft.com/en-us/products/ai-foundry/models/openai) resource. Note the Azure OpenAI endpoint, deployment name, and the key (or ensure you can authenticate with `AzureCliCredential`).
+- Create an [Azure AI Foundry project](https://learn.microsoft.com/azure/ai-foundry/) with an OpenAI model deployment. Note the Foundry project endpoint and deployment name, and ensure you can authenticate with `AzureCliCredential`.
 
 - Install a tool to execute HTTP calls, for example the [REST Client extension](https://marketplace.visualstudio.com/items?itemName=humao.rest-client)
 
@@ -39,8 +39,7 @@ source .venv/bin/activate
 
     - Install Python dependencies – from the sample directory, run `pip install -r requirements.txt` (or the equivalent in your active virtual environment).
 
-    - Copy `local.settings.json.template` to `local.settings.json`, then update `AZURE_OPENAI_ENDPOINT` and `AZURE_OPENAI_CHAT_DEPLOYMENT_NAME` for Azure OpenAI authentication. The samples use `AzureCliCredential` by default, so ensure you're logged in via `az login`.
-        - Alternatively, you can use API key authentication by setting `AZURE_OPENAI_API_KEY` and updating the code to use `AzureOpenAIChatClient()` without the credential parameter.
+    - Copy `local.settings.json.template` to `local.settings.json`, then update `FOUNDRY_PROJECT_ENDPOINT` and `FOUNDRY_MODEL`. The samples use `AzureCliCredential`, so ensure you're logged in via `az login`.
         - Keep `TASKHUB_NAME` set to `default` unless you plan to change the durable task hub name.
 
     - Run the command `func start` from the root of the sample