Add on-chain stream reputation score updated on successful completion for sender ranking

[Chuks-coderr]

Description

Implement a reputation scoring system that increments a per-sender score each time a stream reaches natural completion without cancellation. Reputation scores are stored in contract instance storage, queryable via a getReputation entry point, and can be used by front-ends to surface trustworthy senders.

Acceptance Criteria

• Feature is fully implemented
• Tests pass
• Lint/type checks pass
• PR references this issue number

Notes

⚠️ Do not begin coding until you have been assigned by the maintainer.
Branch as feat/471-contract-reputation-score where N is this issue number.

[kuse-design]

@kuse-design has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

i would like to work on this issue because am a software engineer and am capable of completing this task effectively

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

[Calebstack]

@Calebstack has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hello maintainer, i’ve got this covered! Ready to drop a high-impact, clean PR that gets this merged seamlessly

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