List the projects the authenticated user can access, across workspaces.

A user-credential-only discovery op (no project_id). Projects are flattened across the user's workspaces and tagged with their owning workspace; the answer is what you pass as project_id to a project-scoped request.

Args: request (Request): Incoming request (rate-limit plumbing). response (Response): Outgoing response (rate-limit plumbing). auth (AccountStampedAuth): Account-scope user auth (session token or CLI access JWT); carries the resolved user_id and stamps the per-user rate-limit identity. workspace_id (str | None): Optional filter; when given, only projects in that workspace are returned.

Returns: PublicProjectListResponse: The accessible projects (id, name, workspace_id, workspace_name, workspace_is_demo).