fix(workbench): stabilize investigation presentation rendering

Keep investigation graphs stable during updates, defer expensive chart rendering, and prevent stale results when switching tasks. Adopt reference annotations and consolidate frontend documentation.

src/features/workbench/components/investigation-chart-group.tsx

@@ -1,6 +1,7 @@
 import { useLayoutEffect, useRef, useState, type ReactNode } from "react";
 import { Check, FileText, X } from "lucide-react";
 import { AgentChartView } from "@/features/agent";
+import { DeferredRender } from "@/shared/ui/deferred-render";
 import { formatChartDisplayText } from "@/shared/utils/date-time-text";
 import { Button } from "@/shared/ui/button";
 import { Card, CardContent, CardHeader } from "@/shared/ui/card";
@@ -82,13 +83,13 @@ export function InvestigationChartGroup({ group, reviewing, onCloseChart, refere
         {tile && selected.command.evidence_refs.length ? <Popover><PopoverTrigger asChild><Button type="button" variant="ghost" size="icon-sm" aria-label={`查看图表依据 ${title}`} title="查看图表依据"><FileText size={14} aria-hidden /></Button></PopoverTrigger>
           <PopoverContent align="end" className="workbench-shadcn-surface z-[90] max-h-72 overflow-auto p-2">{references(selected.command.evidence_refs)}</PopoverContent>
         </Popover> : null}
-        <FloatingWindow title={title} fillContent>{() => content(true)}</FloatingWindow>
+        <FloatingWindow title={title} fillContent>{() => <DeferredRender label={`正在加载图表 ${title}`} className="h-full min-h-0">{content(true)}</DeferredRender>}</FloatingWindow>
         <Button type="button" variant="ghost" size="icon-sm" disabled={reviewing} aria-label={`关闭图表 ${title}`}
           onClick={() => group.items.forEach((item) => onCloseChart(item.command.chart_id))}><X size={14} aria-hidden /></Button>
       </div>
     </CardHeader>
     <CardContent className={tile ? "flex min-h-0 flex-1 flex-col px-2 pb-2 pt-0" : "px-3 pb-2 pt-0"}>
-      {content(tile, tile)}
+      <DeferredRender label={`正在加载图表 ${title}`} className={tile ? "h-full min-h-0" : undefined}>{content(tile, tile)}</DeferredRender>
     </CardContent>
   </Card>;
 }