Function create_project 

pub fn create_project(
    config: &mut Config,
    new: &NewProject,
) -> Result<Project, ProjectError>

Create a project, allocating a fresh stable id (FR-001).

Validates the name and dates first, so a refusal yields no registry change. The record is inserted into the in-memory Config; the caller persists it with Config::save, so the atomic write path has exactly one owner.