Change license to AGPLv3+

Affero further protects the project against SaaSS :)

The issue only requests changing the project license to AGPLv3+ and names no files, tests, or entry points. First clarify the licensing implications and obtain a maintainer decision, then identify the repository materials that must reflect the change. Done means the license change is agreed and consistently recorded across the project.

由索引模型根据 Issue 内容生成。