feat(oauth): add OAuth token support

ts/bunq.classes.account.ts

@@ -9,6 +9,7 @@ export interface IBunqConstructorOptions {
   apiKey: string;
   environment: 'SANDBOX' | 'PRODUCTION';
   permittedIps?: string[];
+  isOAuthToken?: boolean; // Set to true when using OAuth access token instead of API key
 }
 
 /**
@@ -35,7 +36,8 @@ export class BunqAccount {
       apiKey: this.options.apiKey,
       environment: this.options.environment,
       deviceDescription: this.options.deviceName,
-      permittedIps: this.options.permittedIps
+      permittedIps: this.options.permittedIps,
+      isOAuthToken: this.options.isOAuthToken
     });
 
     // Initialize API context (handles installation, device registration, session)