Feat: Construct a dynamic variable assignment form #10427 (#11316)

### What problem does this PR solve?

Feat: Construct a dynamic variable assignment form #10427

### Type of change


- [x] New Feature (non-breaking change which adds functionality)

web/src/pages/agent/canvas/node/dropdown/accordion-operators.tsx

@@ -79,8 +79,9 @@ export function AccordionOperators({
               Operator.Code,
               Operator.StringTransform,
               Operator.DataOperations,
+              Operator.VariableAssigner,
               Operator.ListOperations,
-              // Operator.VariableAssigner,
+              Operator.VariableAssigner,
               Operator.VariableAggregator,
             ]}
             isCustomDropdown={isCustomDropdown}

web/src/pages/agent/canvas/node/retrieval-node.tsx

@@ -55,8 +55,8 @@ function InnerRetrievalNode({
                 <div className="flex items-center gap-1.5">
                   <RAGFlowAvatar
                     className="size-6 rounded-lg"
-                    avatar={id}
-                    name={item?.name || (label as string) || 'CN'}
+                    avatar={item?.avatar}
+                    name={item ? item?.name : id}
                   />
 
                   <div className={'truncate flex-1'}>{label || item?.name}</div>