docs: update Bruno API tests for device registration and admin registration

- Fix device registration API test parameters
- Update admin user registration test with proper fields
- Ensure API tests match current endpoint behavior
- Improve API documentation accuracy

bruno/devices/Initiate Device Registration.bru

@@ -5,7 +5,7 @@ meta {
 }
 
 post {
-  url: {{baseUrl}}/api/devices/register
+  url: {{base_url}}/api/devices/register
   body: json
   auth: none
 }