API key authentication does not rotate or scope keys per tenant allowing cross-tenant replay

[Junirezz]

Context
backend/src/auth/apiKey.ts stores apiKey as single global API_KEY env var and checks req.headers['x-api-key'] === API_KEY without tenant scoping.

Why this is a gap
Compromised key works for all tenants and cannot be rotated per tenant without downtime; also no expiry or last-used tracking for audit.

Acceptance Criteria

• Store apiKey per tenantId in apiKey table with hashedKey, scopes[], expiresAt, lastUsedAt
• Middleware checks tenantId from path/query and validates scopes includes required scope for route
• Return 401 API_KEY_EXPIRED or SCOPE_INSUFFICIENT with WWW-Authenticate header
• Test: create two tenants with different keys and assert cross-tenant key gets 401
• Migration adds table, existing single-key still works via fallback env var with deprecation log

[oycodes]

@oycodes has applied to work on this issue as part of the Stellar Wave Program's 9th wave.

Hi Maintainer, I’ve reviewed the issue and believe I can address it effectively. I’d like to take this up and contribute the required fix.

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

[drips-wave]

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

🧑‍💻 @oycodes: 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 🌊