Adds ten editorial diagram types with light, dark, and full-editorial examples; updates the taxonomy, gallery, descriptions, references, and synchronized plugin version; and adds maintainer/visual-proof contribution gates.
Co-authored-by: Jacopo Vendramin <vendraminjacopo@gmail.com>
Add CONTRIBUTING.md covering all validation gates and contribution
workflows, CODE_OF_CONDUCT.md (Contributor Covenant 2.1), GitHub issue
templates (bug/feature), and a pull request template; add a Contributing
section to the README.
