refactor: 移除画布中央常驻空流程提示，引导职责由首访横幅承担

src/renderer/src/canvas/FlowCanvas.tsx

@@ -19,7 +19,6 @@ import { useEditorStore } from "../store/editorStore";
 import { useRunStore } from "../store/runStore";
 import { RpaNode, type RpaNodeData } from "./RpaNode";
 import { ContainerNode, containerSlots, type ContainerNodeData } from "./ContainerNode";
-import { MousePointerClick } from "lucide-react";
 
 const nodeTypes = { rpa: RpaNode, container: ContainerNode };
 
@@ -256,16 +255,6 @@ function CanvasInner({ catalog, onAddAt }: { catalog: Catalog; onAddAt: (compone
           maskColor="rgba(242,245,248,.72)"
         />
       </ReactFlow>
-
-      {flow.nodes.length <= 1 && (
-        <div className="canvas-hint">
-          <MousePointerClick className="icon" />
-          <div>
-            <strong>从左侧拖入能力，开始搭建流程</strong>
-            <span>支持搜索 1016 项目录；单击组件也可追加。</span>
-          </div>
-        </div>
-      )}
     </div>
   );
 }

src/renderer/src/styles/app.css

@@ -2213,49 +2213,9 @@ textarea:focus-visible {
   margin-top: 2px;
 }
 
-.canvas-hint {
-  position: absolute;
-  left: 50%;
-  top: 44%;
-  transform: translate(-50%, -50%);
-  z-index: 4;
-  min-width: 300px;
-  max-width: 420px;
-  padding: 13px 15px;
-  display: flex;
-  gap: 10px;
-  align-items: flex-start;
-  border: 1px solid var(--line);
-  border-radius: 13px;
-  background: rgba(255, 255, 255, 0.92);
-  box-shadow: var(--shadow-panel);
-  backdrop-filter: blur(8px);
-  pointer-events: none;
-}
 
-.canvas-hint .icon {
-  width: 18px;
-  height: 18px;
-  color: var(--blue);
-  flex: none;
-  margin-top: 1px;
-}
 
-.canvas-hint strong {
-  display: block;
-  font-size: 11.5px;
-  font-weight: 700;
-  color: var(--ink);
-  line-height: 17px;
-}
 
-.canvas-hint span {
-  display: block;
-  font-size: 10.5px;
-  color: var(--muted);
-  line-height: 15px;
-  margin-top: 2px;
-}
 
 /* 新建流程首访引导：顶部浮出，5 秒后自动淡出，不接收鼠标事件 */
 .editor-guide {