chore: document Soroban smart contracts deployment and usage

[dotunv]

Problem

The smart contract documentation is minimal:

• contracts/soroban/README.md is generic boilerplate (references a hello_world example that no longer exists)
• No documentation on contract initialization parameters
• No documentation on cross-contract call flow (escrow ↔ milestones)
• No mainnet deployment guide
• No deployment checklist or rollback procedure

Current State

• 3 contracts: crowdpay, escrow, milestones
• crowdpay contract appears unused by the backend (only escrow and milestones are deployed)
• deploy_crowdpay.sh deploys crowdpay but nothing consumes it
• backend/src/scripts/deployContracts.js deploys escrow and milestones
• milestones contract is missing a Makefile

What to Document

1. Contract architecture and relationships
2. Initialization parameters for each contract
3. Cross-contract call flow
4. Deployment steps (testnet and mainnet)
5. Contract upgrade/rollback procedures
6. Whether crowdpay contract should be deprecated or integrated
7. Add Makefile for milestones contract

[Lanhubs]

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

I’d love to take this on! I have strong experience implementing these exact patterns and can deliver a clean, production-ready solution that hits all acceptance criteria.

My approach will focus on writing modular, well-documented code with comprehensive test coverage for both success paths and edge cases.

I'm ready to get started immediately. Could you please assign this to me?

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

[MrG139]

@MrG139 has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hi Maintainer, I’d like to work on this issue
I have experience with relevant tech stack and I’ve reviewed the issue description and acceptance criteria, and I’m confident in delivering a clean, tested solution.
Please kindly assign.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @MrG139 to this issue.

[Caneryy]

@Caneryy 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 issue please.

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

[drips-wave]

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

🧑‍💻 @Lanhubs: 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 marked as completed by a Drips Wave moderator for @Lanhubs as part of the Stellar Wave Program's 7th Wave 🥳

Moderator's reason: [Auto-assessed] The contributor successfully addressed all requirements of the issue, providing comprehensive documentation for the contract architecture, deployment steps, and upgrade procedures, as well as adding the missing Makefile. The PR was merged by a maintainer on 2026-07-27, which serves as conclusive evidence of acceptance.

😎 @Lanhubs: 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.

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

ℹ️ Note: This issue was marked complete via moderation. Points were issued even though the GitHub issue remains open.