Replace in-memory intent creation with on-chain registration

[james2177]

Description

IntentsService.create() in src/intents/intents.service.ts only writes to a local Map. Wire intent creation through to a settlement-contract call so intents exist on-chain, not just in process memory.

Requirements and context

• Must preserve the existing IntentsController.create() response shape so vortex-frontend doesn't break
• Add a feature flag to fall back to in-memory mode during rollout (see issue feat: Soroban RPC read client (/api/v1/chain) #17)

Suggested execution

1. Fork the repo and create a branch

   git checkout -b feature/onchain-intent-create
   

2. Implement changes
   Relevant files:

• src/intents/intents.service.ts
• src/intents/intents.controller.ts

3. Test and commit

   • Run npm run lint && npm run typecheck && npm test && npm run test:e2e
   • Include test output / screenshots or logs demonstrating the fix in the PR

   Example commit message:

   feat: register intents on-chain via settlement contract
   

Guidelines

• Assignment required before starting — comment to claim this issue
• PR description must include: Closes #[this issue's number]
• Timeframe: 96 hours from assignment
• Complexity: High (200 points)

---

Part of the Drips Wave for vortex-backend.

[Niffy03]

@Niffy03 has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hi, I'd like to work on this.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Niffy03 to this issue.

[chideraisiguzor]

@chideraisiguzor has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Smart contract developer building secure, production-ready blockchain systems in Rust and Solidity. I use the Stellar SDK to ship Web3 solutions that move real value — not just demos.

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

[drips-wave]

Congratulations, @chideraisiguzor! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on July 30, 2026.

🧑‍💻 @chideraisiguzor: 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 @chideraisiguzor as part of the Stellar Wave Program's 7th Wave 🥳

😎 @chideraisiguzor: 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.