### 🧩 Add modular reward strategy system

[El-swaggerito]

Overview
Allow swapping reward calculation logic.

Acceptance Criteria

• Strategy pattern implemented

Labels: enhancement, advanced

[Adeyemi-cmd]

@Adeyemi-cmd has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

I’ve worked with strategy-pattern designs before, so I’ll refactor the reward system into a modular strategy-based setup where different reward calculation logics can be swapped cleanly without touching core flow.

I’ll make sure the base interface is consistent, implementations are plug-and-play, and existing behavior is preserved while allowing future reward models to scale safely.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Adeyemi-cmd to this issue.