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-presentation-panel.tsx

@@ -5,6 +5,7 @@ import type { AnswerUiBlock } from "@/features/agent";
 import { Badge } from "@/shared/ui/badge";
 import { Button } from "@/shared/ui/button";
 import { Card, CardContent, CardHeader } from "@/shared/ui/card";
+import { LoadingSkeleton } from "@/shared/ui/deferred-render";
 import {
   PresentationItem,
   PresentationViewport,
@@ -211,6 +212,9 @@ export function InvestigationPresentationPanel({
                 {error}
               </p>
             ) : null}
+            {!reviewing && !localPreview && status === "connecting" && !charts.length && !blocks.length ? (
+              <LoadingSkeleton label="正在加载调查展示" />
+            ) : null}
             <AnimatePresence initial={false} mode="popLayout">
               {cameraPaused ? (
                 <PresentationItem key="camera" immediate={immediate}>
@@ -318,6 +322,7 @@ export function InvestigationPresentationPanel({
             !overlay &&
             !blocks.length &&
             !records.length &&
+            status !== "connecting" &&
             !relatedLayers.length ? (
               <p className="text-xs leading-5 text-muted-foreground">
                 当前没有展示结果，可切换历史动作回看地图与结果。