[Feature] Implement Discourse Engagement Adapter

[mijinummi]

Discourse Adapter (Governance Engagement)

Description
Many DAOs use Discourse for long-form governance discussions. This task involves creating a new adapter within packages/adapters to fetch user engagement metrics—such as posts created and likes received—via the Discourse API.

Task

• Create discourse.adapter.ts
• Implement the standard IContributorAdapter interface

Goal
Enable DAOs to recognize and reward thoughtful, high-quality forum participation as part of their contribution scoring.