Add Webhooks endpoints

[karlwaldman]

Overview

Add support for webhook management.

Endpoints to Add

• GET /v1/webhooks - List all webhooks
• POST /v1/webhooks - Create new webhook
• DELETE /v1/webhooks/{webhook_id} - Delete webhook

Types Needed

• Webhook
• WebhooksResponse
• CreateWebhookOptions

Priority

P1 - High Value - Critical for real-time integrations

Note

This will require adding POST/DELETE HTTP method support to the client (currently only supports GET).

Swagger Reference

See swagger/v1/swagger.json in oilpriceapi-api repo for schema details