chore: add Apache 2.0 license + NOTICE + TRADEMARK

- Apache 2.0 (OSI-approved open source)
- NOTICE: attribution requirement per Section 4(d)
- TRADEMARK.md: brand protection policy
- CLA required for all contributions

Part of MushroomDAO license unification.
See: https://github.com/MushroomDAO/launch/tree/main/docs/license

Author: jhfnetboy