chore: Amend license from MIT to AGPLv3

[dan-menlo]

Folks, I've submitted a PR to shift Nitro from MIT license to AGPL, as per our retreat discussion.

Why AGPL?

• Jan wants to build Nitro as a long-term ecosystem, and will drive Nitro's development for next few years
• We want strong copyleft culture, where downstream consumers improvements are fed back into the ecosystem
• We will be investing a lot of effort into integrating TensorRT-LLM and other libraries, and want potential Jan competitors to compete with us on an even playing field
• Longer-term, we can consider a dual-licensing scheme for Nitro, to waive AGPL with a commercial license (ala MySQL)

Who else uses AGPLv3?

• MongoDB
• Minio
• Increasing numbers of the r/selfhosted stack uses AGPL, and we maintain license compatibility

cc @tikikun @vuonghoainam @0xSage

[tikikun]

LGTM