fix(webhooks): persist secrets to DB with AES-256-GCM encryption, use…

[GreyDayo]

… top-level crypto import

Closes #606
Closes #607

Issue #606 (high): WebhooksService stored webhook registration secrets in an in-memory Map — lost on every restart, unencrypted, not shared across instances. Persistence to the database was added under #482; this commit completes #606 by encrypting secrets at rest with AES-256-GCM.

• Added WEBHOOK_SECRET_KEY env var (opt-in). When set, secrets are encrypted via AES-256-GCM (randomised IV per secret, auth tag stored alongside ciphertext as 'enc:::'). When unset a startup warning is emitted and secrets are stored as plain text for backward compatibility.
• decryptSecret() handles both encrypted and legacy plain-text rows transparently so existing registrations remain readable after the key is added.
• Documented WEBHOOK_SECRET_KEY in .env.example with a generation command.

Issue #607 (low): signPayload() was using require('crypto') at runtime, inconsistent with the rest of the codebase and inhibiting tree-shaking. The fix uses the existing top-level import * as crypto already in the file.

Tests: updated build() helper to accept a mock ConfigService; added four new tests covering encrypted storage, round-trip decryption, plain-text backward compatibility, and signPayload HMAC correctness.

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

• 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]

@GreyDayo 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