Dockerfile and docker-compose for API + Postgres

[greatest0fallt1me]

Description

Add multi-stage Dockerfile for the backend and docker-compose with Postgres for local dev.

Requirements and context

• Non-root user in image.
• Healthcheck uses /health.

Suggested execution

• Fork the repository and create a branch (example below).
• Implement changes in StreamPay-Backend (TypeScript / Express per package.json).
• Keep the service secure, tested, and documented; prefer small, reviewable PRs.

git checkout -b chore/docker-compose-backend

Implementation targets

• Dockerfile, docker-compose.yml at repo or StreamPay-Backend/.

Tests and validation

• CI optional: build image only.

• Run npm test and npm run lint in StreamPay-Backend.

• Cover edge cases; include test output and brief security notes in the PR description.

Guidelines

• Target minimum 95% test coverage on new or changed backend code (or justify gaps).
• Clear documentation (OpenAPI / README / inline docs as specified).
• Timeframe: 96 hours from assignment.

Example commit message

chore(backend): Docker and compose for local development

[solomonadzape95]

@solomonadzape95 has applied to work on this issue as part of the Stellar Wave Program's 3rd wave.

Hi team, I would like to work on this issue. I've gone through the details thoroughly and I understand what is needed here. I believe I have the sufficient skills to provide the necessary deliverables. My deliverables are quality code within an ETA of 4 to 6hrs of assignment

ℹ️ Repo Maintainers: To accept this application, review their application or assign @solomonadzape95 to this issue.

[drips-wave]

Congratulations, @solomonadzape95! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on March 30, 2026.

🧑‍💻 @solomonadzape95: 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 🌊