fix: restore imports lost during merge in App.tsx

The merge of origin/dev into PSL-US-33784 incorrectly resolved the
import block in App.tsx, dropping:
- closing brace and source for @fluentui/react-components
- SparkleRegular import from @fluentui/react-icons
- App.css stylesheet import
- ChatHistoryPanel component import

This caused the Docker build-and-push CI job to fail with:
  SyntaxError: Unexpected keyword 'import'. (11:0)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: AjitPadhi-Microsoft

src/App/src/App.tsx

@@ -8,6 +8,10 @@ import {
   FluentProvider,
   Subtitle2,
   webLightTheme,
+} from "@fluentui/react-components";
+import { SparkleRegular } from "@fluentui/react-icons";
+import "./App.css";
+import { ChatHistoryPanel } from "./components/ChatHistoryPanel/ChatHistoryPanel";
 import { getUserInfo } from "./api/api";
 import { useAppDispatch, useAppSelector } from "./state/hooks";
 import {