List Sessions

List chat sessions for the authenticated user.

Returns a paginated list of chat sessions belonging to the current user, with pinned sessions first and most-recently-updated as the tiebreaker.

Args: user_id: The authenticated user's ID. limit: Maximum number of sessions to return (1-100). offset: Number of sessions to skip for pagination. expert_id: Restrict the listing to sessions scoped to this expert. pinned_first: Whether pinned sessions precede strict recency ordering.

Returns: ListSessionsResponse: List of session summaries and total count.