feat: add platform key usage to mcp auth

apps/ui/js/api-keys.js

@@ -5,9 +5,9 @@ var search = '';
 
 var SCOPES = ['read', 'write', 'deploy'];
 var SCOPE_DESC = {
-  read: 'Read operations, logs, and usage',
-  write: 'Create and update operations',
-  deploy: 'Publish agents and operations',
+  read: 'Initialize MCP sessions and list tools',
+  write: 'Execute published tools through MCP',
+  deploy: 'Reserved for deploy-scoped automation',
 };
 
 function mapKeyRecord(record) {