feat: Normalize headers to lowercase keys and export WebhookVerificationError (#12)

* Normalize headers to lowercase before passing to svix

* Export Seam aliased svix WebhookVerificationError

* ci: Format code

---------

Co-authored-by: Seam Bot <devops@getseam.com>

Author: andrii-balitskyi

src/lib/index.ts

@@ -1 +1,2 @@
 export * from './seam-webhook.js'
+export { WebhookVerificationError as SeamWebhookVerificationError } from 'svix'

src/lib/seam-webhook.ts

@@ -9,6 +9,10 @@ export class SeamWebhook {
   }
 
   verify(payload: string, headers: Record<string, string>): SeamEvent {
-    return this.#webhook.verify(payload, headers) as SeamEvent
+    const normalizedHeaders = Object.fromEntries(
+      Object.entries(headers).map(([key, value]) => [key.toLowerCase(), value]),
+    )
+
+    return this.#webhook.verify(payload, normalizedHeaders) as SeamEvent
   }
 }