Python: Replace Pydantic Settings with TypedDict + load_settings() (#3843)

* Replace Pydantic Settings with TypedDict + load_settings()

- Remove pydantic-settings dependency, add python-dotenv
- Delete _pydantic.py (AFBaseSettings, HTTPsUrl)
- Add _settings.py with generic load_settings() function, SecretString,
  type coercion, and Required field validation (SettingNotFoundError)
- Convert all 13 settings classes from AFBaseSettings subclasses to
  TypedDict definitions with load_settings() calls
- Update all consumers from attribute access to dict access
- Add 20 unit tests for load_settings() covering basic loading, dotenv,
  SecretString, type coercion, and required field validation
- Update all existing tests for new settings patterns

* Fix mypy type errors from settings conversion

- Fix str | None attribute access in responses_client (walrus operator)
- Fix SecretString | None narrowing in bedrock (type: ignore after guard)
- Convert _context_provider.py attribute access to dict access (missed file)
- Fix endpoint type narrowing in search_provider and context_provider
- Fix purview: str | None .rstrip(), int | None defaults, urlparse bytes

* Address PR review: required_fields param, type validation, fixes

- Move required field validation from TypedDict annotations (Required)
  to a required_fields parameter on load_settings(), enabling runtime
  decisions about which fields are required
- Remove Required imports and restore from __future__ import annotations
  in ollama and foundry_local
- Add _check_override_type() for deterministic ServiceInitializationError
  on invalid override types (e.g. dict passed for str field)
- Fix all multi-exception test catches back to single exception type
- Fix Ollama host=None: use .get() so None is passed through to SDK default
- Fix Purview processor: use explicit is-None checks instead of or operator
- Remove unused BaseModel import from openai/_shared.py
- Add 4 new tests (24 total): required_fields param, type validation

* Fix type validation: allow int for float fields

_check_override_type now permits int values for float-typed fields,
matching Python's standard numeric promotion behavior.

* fix: wrap urlparse arg with str() to fix mypy bytes endswith error

python/packages/copilotstudio/tests/test_copilot_agent.py

@@ -38,49 +38,57 @@ class TestCopilotStudioAgent:
         return MagicMock(spec=CopilotClient)
 
     @patch("agent_framework_copilotstudio._acquire_token.acquire_token")
-    @patch("agent_framework_copilotstudio._agent.CopilotStudioSettings")
-    def test_init_missing_environment_id(self, mock_settings: MagicMock, mock_acquire_token: MagicMock) -> None:
+    @patch("agent_framework_copilotstudio._agent.load_settings")
+    def test_init_missing_environment_id(self, mock_load_settings: MagicMock, mock_acquire_token: MagicMock) -> None:
         mock_acquire_token.return_value = "fake-token"
-        mock_settings.return_value.environmentid = None
-        mock_settings.return_value.schemaname = "test-bot"
-        mock_settings.return_value.tenantid = "test-tenant"
-        mock_settings.return_value.agentappid = "test-client"
+        mock_load_settings.return_value = {
+            "environmentid": None,
+            "schemaname": "test-bot",
+            "tenantid": "test-tenant",
+            "agentappid": "test-client",
+        }
 
         with pytest.raises(ServiceInitializationError, match="environment ID is required"):
             CopilotStudioAgent()
 
     @patch("agent_framework_copilotstudio._acquire_token.acquire_token")
-    @patch("agent_framework_copilotstudio._agent.CopilotStudioSettings")
-    def test_init_missing_bot_id(self, mock_settings: MagicMock, mock_acquire_token: MagicMock) -> None:
+    @patch("agent_framework_copilotstudio._agent.load_settings")
+    def test_init_missing_bot_id(self, mock_load_settings: MagicMock, mock_acquire_token: MagicMock) -> None:
         mock_acquire_token.return_value = "fake-token"
-        mock_settings.return_value.environmentid = "test-env"
-        mock_settings.return_value.schemaname = None
-        mock_settings.return_value.tenantid = "test-tenant"
-        mock_settings.return_value.agentappid = "test-client"
+        mock_load_settings.return_value = {
+            "environmentid": "test-env",
+            "schemaname": None,
+            "tenantid": "test-tenant",
+            "agentappid": "test-client",
+        }
 
         with pytest.raises(ServiceInitializationError, match="agent identifier"):
             CopilotStudioAgent()
 
     @patch("agent_framework_copilotstudio._acquire_token.acquire_token")
-    @patch("agent_framework_copilotstudio._agent.CopilotStudioSettings")
-    def test_init_missing_tenant_id(self, mock_settings: MagicMock, mock_acquire_token: MagicMock) -> None:
+    @patch("agent_framework_copilotstudio._agent.load_settings")
+    def test_init_missing_tenant_id(self, mock_load_settings: MagicMock, mock_acquire_token: MagicMock) -> None:
         mock_acquire_token.return_value = "fake-token"
-        mock_settings.return_value.environmentid = "test-env"
-        mock_settings.return_value.schemaname = "test-bot"
-        mock_settings.return_value.tenantid = None
-        mock_settings.return_value.agentappid = "test-client"
+        mock_load_settings.return_value = {
+            "environmentid": "test-env",
+            "schemaname": "test-bot",
+            "tenantid": None,
+            "agentappid": "test-client",
+        }
 
         with pytest.raises(ServiceInitializationError, match="tenant ID is required"):
             CopilotStudioAgent()
 
     @patch("agent_framework_copilotstudio._acquire_token.acquire_token")
-    @patch("agent_framework_copilotstudio._agent.CopilotStudioSettings")
-    def test_init_missing_client_id(self, mock_settings: MagicMock, mock_acquire_token: MagicMock) -> None:
+    @patch("agent_framework_copilotstudio._agent.load_settings")
+    def test_init_missing_client_id(self, mock_load_settings: MagicMock, mock_acquire_token: MagicMock) -> None:
         mock_acquire_token.return_value = "fake-token"
-        mock_settings.return_value.environmentid = "test-env"
-        mock_settings.return_value.schemaname = "test-bot"
-        mock_settings.return_value.tenantid = "test-tenant"
-        mock_settings.return_value.agentappid = None
+        mock_load_settings.return_value = {
+            "environmentid": "test-env",
+            "schemaname": "test-bot",
+            "tenantid": "test-tenant",
+            "agentappid": None,
+        }
 
         with pytest.raises(ServiceInitializationError, match="client ID is required"):
             CopilotStudioAgent()
@@ -93,11 +101,13 @@ class TestCopilotStudioAgent:
     @patch("agent_framework_copilotstudio._acquire_token.acquire_token")
     def test_init_empty_environment_id(self, mock_acquire_token: MagicMock) -> None:
         mock_acquire_token.return_value = "fake-token"
-        with patch("agent_framework_copilotstudio._agent.CopilotStudioSettings") as mock_settings:
-            mock_settings.return_value.environmentid = ""
-            mock_settings.return_value.schemaname = "test-bot"
-            mock_settings.return_value.tenantid = "test-tenant"
-            mock_settings.return_value.agentappid = "test-client"
+        with patch("agent_framework_copilotstudio._agent.load_settings") as mock_load_settings:
+            mock_load_settings.return_value = {
+                "environmentid": "",
+                "schemaname": "test-bot",
+                "tenantid": "test-tenant",
+                "agentappid": "test-client",
+            }
 
             with pytest.raises(ServiceInitializationError, match="environment ID is required"):
                 CopilotStudioAgent()
@@ -105,11 +115,13 @@ class TestCopilotStudioAgent:
     @patch("agent_framework_copilotstudio._acquire_token.acquire_token")
     def test_init_empty_schema_name(self, mock_acquire_token: MagicMock) -> None:
         mock_acquire_token.return_value = "fake-token"
-        with patch("agent_framework_copilotstudio._agent.CopilotStudioSettings") as mock_settings:
-            mock_settings.return_value.environmentid = "test-env"
-            mock_settings.return_value.schemaname = ""
-            mock_settings.return_value.tenantid = "test-tenant"
-            mock_settings.return_value.agentappid = "test-client"
+        with patch("agent_framework_copilotstudio._agent.load_settings") as mock_load_settings:
+            mock_load_settings.return_value = {
+                "environmentid": "test-env",
+                "schemaname": "",
+                "tenantid": "test-tenant",
+                "agentappid": "test-client",
+            }
 
             with pytest.raises(ServiceInitializationError, match="agent identifier"):
                 CopilotStudioAgent()