fix(python): use typed annotations in _handle_permission_request

Use PermissionRequest and PermissionRequestResult types instead of
plain dict to fix ty type checker errors from stricter enforcement.

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

Author: SteveSandersonMS

python/copilot/session.py

@@ -14,6 +14,8 @@
 from .generated.session_events import SessionEvent, SessionEventType, session_event_from_dict
 from .types import (
     MessageOptions,
+    PermissionRequest,
+    PermissionRequestResult,
     SessionHooks,
     Tool,
     ToolHandler,
@@ -308,7 +310,7 @@ def _register_permission_handler(self, handler: Optional[_PermissionHandlerFn])
         with self._permission_handler_lock:
             self._permission_handler = handler
 
-    async def _handle_permission_request(self, request: dict) -> dict:
+    async def _handle_permission_request(self, request: PermissionRequest) -> PermissionRequestResult:
         """
         Handle a permission request from the Copilot CLI.