Implement subscription smart contract oracle integration for price feeds

[Smartdevs17]

Description

Integrate on-chain price oracles for subscription pricing in stablecoins or volatile tokens, ensuring fair market-rate conversions at billing time.

Acceptance Criteria

• Oracle price feed integration (Stellar DEX, Band Protocol)
• Price lookup at billing execution time
• Slippage protection with max/min price bounds
• Oracle health monitoring with fallback
• Gas-efficient oracle calls (cached with TTL)
• Subscription price in fiat equivalent display

Technical Scope

• contracts/subscription/src/lib.rs
• contracts/oracle/
• backend/services/
• Edge: oracle staleness during volatility, price manipulation at billing boundary

[GauravKarakoti]

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

Allow me to work on this one

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

[iyanumajekodunmi756]

@iyanumajekodunmi756 has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

I am interested in working on this issue and i shall deliver promptly on this with qualitatively feedback

ℹ️ Repo Maintainers: To accept this application, review their application or assign @iyanumajekodunmi756 to this issue.

[Itodo-S]

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

please let me work on this; I can handle it.

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

[drips-wave]

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

🧑‍💻 @Itodo-S: 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.

Warning

When opening a PR, please link it to this issue to ensure it gets tracked accurately. Points are awarded when this issue is marked as completed by the maintainer.

🤠 Repo maintainers: Please keep an eye on the contributor's progress and review their work before the due date. You can manage this issue, including adjusting its complexity and points, here.

🌊 Happy Wave 🌊

[drips-wave]

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

😎 @Itodo-S: You earned 200 Points for completing this issue! After the current Wave ends, you'll be eligible for a percentage of the Wave's reward pool based on the percentage of total points you've earned. Learn more here. You can also Leave a review to share your experience working on this issue.

🧑‍💻 Repo maintainers: How'd the contributor do? Leave a review to share your experience working with them.