Python: Fix: Parse oauth_consent_request events in Azure AI client (#4197)

* Fix: Parse oauth_consent_request events in Azure AI client (#3950)

When Azure AI Agent Service returns an oauth_consent_request output item
for OAuth-protected MCP tools, the base OpenAI responses parser drops it
(hits case _ default branch). This causes agent runs to complete silently
with zero content.

Changes:
- Add oauth_consent_request ContentType and Content.from_oauth_consent_request()
  factory with consent_link field and user_input_request=True
- Override _parse_response_from_openai and _parse_chunk_from_openai in
  RawAzureAIClient to intercept Azure-specific oauth_consent_request items
- Add _emit_oauth_consent helper in AG-UI to emit CustomEvent for frontends
- Add tests proving base parser drops the event and Azure AI override catches it

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

* addressed comment

* addressed comments

* addressed comments

---------

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

python/packages/core/tests/core/test_types.py

@@ -3424,3 +3424,30 @@ class TestResponseStreamEdgeCases:
 
 
 # endregion
+
+
+# region OAuth Consent Content
+
+
+def test_oauth_consent_request_creation():
+    """Test Content.from_oauth_consent_request creates the correct content."""
+    content = Content.from_oauth_consent_request(
+        consent_link="https://login.microsoftonline.com/common/oauth2/authorize?client_id=abc",
+    )
+    assert content.type == "oauth_consent_request"
+    assert content.consent_link == "https://login.microsoftonline.com/common/oauth2/authorize?client_id=abc"
+    assert content.user_input_request is True
+
+
+def test_oauth_consent_request_serialization_roundtrip():
+    """Test that oauth_consent_request content serializes and includes consent_link."""
+    content = Content.from_oauth_consent_request(
+        consent_link="https://login.microsoftonline.com/consent",
+    )
+    d = content.to_dict()
+    assert d["type"] == "oauth_consent_request"
+    assert d["consent_link"] == "https://login.microsoftonline.com/consent"
+    assert d["user_input_request"] is True
+
+
+# endregion