fix(voice-call): derive SSRF allowedHostnames from baseUrl for non-US regions

getCallStatus had a hardcoded allowedHostnames of ['api.twilio.com'], which
causes the SSRF guard to reject requests for non-US regional endpoints
(e.g. api.dublin.ie1.twilio.com). The error was silently swallowed, breaking
call status polling for all non-US region deployments.

Derive the hostname dynamically from this.baseUrl instead. The baseUrl is
constructed from Zod-validated config (region/edge with regex constraints),
so SSRF protection is preserved.

extensions/voice-call/src/providers/twilio.ts

@@ -731,7 +731,7 @@ export class TwilioProvider implements VoiceCallProvider {
           Authorization: `Basic ${Buffer.from(`${this.accountSid}:${this.authToken}`).toString("base64")}`,
         },
         allowNotFound: true,
-        allowedHostnames: ["api.twilio.com"],
+        allowedHostnames: [new URL(this.baseUrl).hostname],
         auditContext: "twilio-get-call-status",
         errorPrefix: "Twilio get call status error",
       });