Implement subscription transaction batching and aggregation

[Smartdevs17]

Description

Batch multiple subscription transactions (charges, refunds) into a single on-chain operation to reduce gas costs and improve efficiency.

Acceptance Criteria

• Transaction batching contract with Merkle verification
• Charge aggregation (combine multiple charges in one tx)
• Refund batching for efficiency
• Batch settlement with per-item status tracking
• Gas cost reduction measurement (target: 60%)
• Batch queue management with priority

Technical Scope

• contracts/batch/
• app/services/batchTransactionService.ts
• Edge: partial batch failure, gas limit estimation, concurrent batch submissions

[Ebenezer199914]

@Ebenezer199914 has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

i will like to work on this

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Ebenezer199914 to this issue.

[rohan911438]

@rohan911438 has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Would love to work on it

ℹ️ Repo Maintainers: To accept this application, review their application or assign @rohan911438 to this issue.

[drips-wave]

Congratulations, @rohan911438! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 2, 2026.

🧑‍💻 @rohan911438: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

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[drips-wave]

This issue has been completed by @rohan911438 as part of the Stellar Wave Program's 5th Wave 🥳

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