Fic declatation of baseUrl to ensure it includes /api/v3 whether provided or not.

src/lib/base.ts

@@ -8,10 +8,17 @@ export interface ApiResult<T> {
 }
 
 export class BaseClient {
+    protected readonly baseUrl: string;
+    
     constructor(
-        protected readonly baseUrl: string,
+        baseUrl: string,
         protected readonly apiKey?: string
-    ) {}
+    ) {
+        const root = baseUrl.replace(/\/$/, '');
+        this.baseUrl = root.endsWith('/api/v3')
+            ? root
+            : `${root}/api/v3`;
+    }
 
     /**
      * Handles the Envelope logic