Feat: Modify the style of the agent page bright theme #3221 (#9162)

### What problem does this PR solve?

Feat: Modify the style of the agent page bright theme #3221

### Type of change


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

web/src/pages/agent/canvas/node/handle.tsx

@@ -36,7 +36,7 @@ export function CommonHandle({
           showModal();
         }}
       >
-        <Plus className="size-3 pointer-events-none" />
+        <Plus className="size-3 pointer-events-none text-text-title-invert" />
         {visible && (
           <InnerNextStepDropdown hideModal={hideModal}>
             <span></span>