refactor(canvas): 浮层体系重构 — z-index 14档+专注模式+工具栏click触发 #126 #127 #128 (#129)

按视觉层重设计 z-index（12→14 档），新增节点层/激活节点层/节点工具栏层等
语义 token，并下沉节点内部 stacking context（--node-z-content/overlay/handle）
与 dock 子面板（--dock-z-popover），消除硬编码 z 值。

新增专注模式（避让分屏可切换）：use-focus-mode 管理 localStorage 偏好与小屏
（<1024px）强制避让；助手面板从 flex 改为 absolute + 垂直分槽（顶部 288px
让位活动任务面板），画布区按面板宽度动态 padding；顶栏新增 PanelRight
切换按钮并带强制态反馈。

节点工具栏由 hover+select 触发放为 click-only（选中即显），组件由
canvas-node-hover-toolbar 重命名为 canvas-node-toolbar；移除 project 与
render-model 中冗余的 toolbarNodeId 状态。

活动任务面板 z-index 由 --z-modal-overlay(110) 降至 --z-panel-floating(80)，
归位浮动面板层；AGENTS.md Elevation 同步至 14 档。

Co-authored-by: sikongyue <3155157671@qq.com>

web/src/pages/canvas/shared.tsx

@@ -5,7 +5,7 @@ import { Link, useParams } from "react-router";
 import { nanoid } from "nanoid";
 
 import { ConnectionPath } from "@/components/canvas/canvas-connections";
-import { CanvasNodeHoverToolbar, CanvasNodeInfoModal } from "@/components/canvas/canvas-node-hover-toolbar";
+import { CanvasNodeToolbar, CanvasNodeInfoModal } from "@/components/canvas/canvas-node-toolbar";
 import { CanvasFrameNode } from "@/components/canvas/canvas-frame-node";
 import { CanvasNode } from "@/components/canvas/canvas-node";
 import { CanvasZoomControls } from "@/components/canvas/canvas-zoom-controls";
@@ -215,7 +215,7 @@ export default function SharedCanvasPage() {
         };
     }));
     const renderSharedNode = useCallback((node: CanvasNodeData): ReactNode => node.type === CanvasNodeType.Script ? <SharedScriptNode node={node} onUnauthorized={unauthorized} /> : <SharedConfigNode node={node} onUnauthorized={unauthorized} />, [unauthorized]);
-    const toolbarNodeKey = toolbarNodeId || selectedNodeId;
+    const toolbarNodeKey = selectedNodeId;
     const toolbarNode = toolbarNodeKey ? nodeById.get(toolbarNodeKey) || null : null;
 
     if (loading) return <FullScreenLoader label="正在打开共享画布" detail="读取节点、连线和视图状态" />;
@@ -256,7 +256,7 @@ export default function SharedCanvasPage() {
                 }} onHoverStart={keepToolbar} onHoverEnd={hideToolbar} onConnectStart={unauthorized} onResize={() => undefined} onContentChange={unauthorized} onRetry={unauthorized} onCancelTask={unauthorized} onOpenTaskDetails={unauthorized} onViewImage={(target) => setInfoNodeId(target.id)} onContextMenu={(event, nodeId) => openContextMenu(event, nodeId)} />)}
             </InfiniteCanvas>
 
-            <CanvasNodeHoverToolbar node={dragRef.current ? null : toolbarNode} viewport={viewport} containerRef={containerRef} onKeep={keepToolbar} onLeave={hideToolbar} onInfo={(node) => setInfoNodeId(node.id)} onEditText={unauthorized} onDecreaseFont={unauthorized} onIncreaseFont={unauthorized} onToggleDialog={unauthorized} onAnnotate={unauthorized} onGenerateImage={unauthorized} onUpload={unauthorized} onDownload={unauthorized} onSaveAsset={unauthorized} onMaskEdit={unauthorized} onEmotion={unauthorized} onPortraitTexture={unauthorized} onCrop={unauthorized} onSplit={unauthorized} onUpscale={unauthorized} onSuperResolve={unauthorized} onAngle={unauthorized} onViewImage={unauthorized} onExtractVideoLastFrame={unauthorized} extractingVideoFrame={false} onReversePrompt={unauthorized} onRetry={unauthorized} onToggleFreeResize={unauthorized} onToggleLocked={unauthorized} onDelete={unauthorized} />
+            <CanvasNodeToolbar node={dragRef.current ? null : toolbarNode} viewport={viewport} containerRef={containerRef} onKeep={keepToolbar} onLeave={hideToolbar} onInfo={(node) => setInfoNodeId(node.id)} onEditText={unauthorized} onDecreaseFont={unauthorized} onIncreaseFont={unauthorized} onToggleDialog={unauthorized} onAnnotate={unauthorized} onGenerateImage={unauthorized} onUpload={unauthorized} onDownload={unauthorized} onSaveAsset={unauthorized} onMaskEdit={unauthorized} onEmotion={unauthorized} onPortraitTexture={unauthorized} onCrop={unauthorized} onSplit={unauthorized} onUpscale={unauthorized} onSuperResolve={unauthorized} onAngle={unauthorized} onViewImage={unauthorized} onExtractVideoLastFrame={unauthorized} extractingVideoFrame={false} onReversePrompt={unauthorized} onRetry={unauthorized} onToggleFreeResize={unauthorized} onToggleLocked={unauthorized} onDelete={unauthorized} />
 
             <div className="absolute bottom-5 left-5 z-[var(--z-panel-floating)]"><CanvasZoomControls scale={viewport.k} containerRef={containerRef} onScaleChange={setZoom} onReset={resetViewport} isMiniMapOpen={false} onToggleMiniMap={unauthorized} onOpenShortcuts={unauthorized} /></div>
             <div className="pointer-events-none absolute bottom-5 right-5 z-[var(--z-panel-floating)] max-w-[340px] text-right text-xs leading-5" style={{ color: theme.node.muted }}>访客操作仅在当前页面临时生效</div>