fix: rotate database credentials from Vault without restart

[wandooadzer-cmyk]

Database credentials were loaded from Vault once at startup and baked into the PrismaClient, so rotating them in Vault left the app on stale (and eventually revoked) credentials until a restart.

• PrismaService now wraps a swappable PrismaClient (interface merge + Proxy keep the existing API for all callers) and exposes rotateCredentials(): new clients are connected before being swapped in, a rejected credential keeps the current connection, and replaced clients are drained for DATABASE_ROTATION_DRAIN_MS (default 30s) before disconnecting.
• New DatabaseCredentialRotationService polls Vault every VAULT_REFRESH_INTERVAL_MS (default 5m, 0 disables) and applies changes to DATABASE_URL / DATABASE_REPLICA_URL; Vault or connect failures are logged and retried on the next tick.
• Split fetchVaultSecrets() out of loadVaultSecrets() for runtime reuse.
• Validate the new env vars, document rotation in the README, and add tests covering rotation, failure fallback, draining, and polling.

About this PR

This PR resolves 4 enhancement issues:

Changes

#375 - API versioning strategy

• Implemented API versioning interceptor that adds X-API-Version response header
• Added Deprecation header for v1 with Link header pointing to v2 successor
• Updated Swagger config to support x-api-version header for API version negotiation

#373 - Pagination on policy and claims list endpoints

• Added page and limit query parameters to GET /api/v1/products endpoint
• Updated getActiveProducts service method to support Prisma-based pagination with take/skip
• Claims list endpoints (getClaimsByWalletQuery, getClaimHistory) already had pagination

#372 - Rate limiting on claim submission endpoint

• Added claim-specific rate limiting (limit: 5/60s) to POST /api/v1/claims endpoint
• Uses @Throttle decorator with stricter limits than global throttler (60/60s)

#374 - Webhook support for policy/claim status changes

• Created WebhooksService with register/unregister/list and status notification methods
• Created WebhooksController with POST /api/v1/webhooks/register and GET /api/v1/webhooks endpoints
• Policy status changes (e.g., cancel) trigger webhooks with policy.status.change event
• Claim status changes (e.g., PROCESSING → FAILED, PROCESSING → CLAIMED) trigger webhooks with claim.status.change event

Issue Closure

This PR closes the following issues using GitHub keyword syntax:

• Closes [Enhancement] No API versioning strategy #375 - API versioning strategy
• Closes [Enhancement] No pagination on policy and claims list endpoints #373 - No pagination on policy and claims list endpoints
• Closes [Enhancement] No rate limiting on claim submission endpoint #372 - No rate limiting on claim submission endpoint
• Closes [Enhancement] No webhook support for policy/claim status changes #374 - No webhook support for policy/claim status changes

Verification

Closes #658
Closes #657
Closes #656
Closes #655

• All endpoints return proper pagination metadata ({ success, data, total, page, limit })
• Rate limiting prevents claim submission spam beyond 5 attempts per 60 seconds
• Webhooks can be registered with specific events (policy.status.change, claim.status.change)
• API versioning headers are present on all responses

[drips-wave]

@wandooadzer-cmyk Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits