Enable GitHub Discussions for community interaction

[4444J99]

Participants felt the project was broadcast-only and lacked a place for community interaction. Enabling and linking Discussions will help.

[4444J99]

Engagement disposition: evolving. Main now points readers to GitHub Discussions from README.md, profile/README.md, CONTRIBUTING.md, QUICK_START.md, and the validation ledgers, but live repo settings still report hasDiscussionsEnabled=false for organvm/dot-github--logos. The documentation is ahead of the platform setting; the next real step is enabling Discussions and verifying the link resolves to an active board.