docs: update license from AGPL to PMPL

- Replace AGPL-3.0-or-later with PMPL-1.0-or-later
- Update license name and URLs
- Align with palimpsest-license standard

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: Your Name

README.adoc

@@ -145,7 +145,7 @@ sanctify export --guix ./project/ | aegis apply
 
 == License
 
-AGPL-3.0-or-later
+PMPL-1.0-or-later
 
 == Related Projects