chore: bulk dependency updates + fix immer v11 default import + sentry test

Package updates (safe minor/major bumps, all build-verified):
- @tanstack/react-query 5.24->5.100, react-virtual 3.2->3.13
- jotai 2.6->2.20, immer 9->11, dayjs, chroma-js, classnames, blurhash
- slate/slate-dom/slate-react 0.123->0.124
- focus-trap-react 10->12, react-error-boundary 4->6
- html-dom-parser 4->7, html-react-parser 4->6
- pdfjs-dist 4->5, ua-parser-js 1->2
- i18next-http-backend 3->4, i18next-browser-languagedetector 8.0->8.2
- react-aria 3.29->3.48, matrix-widget-api 1.16->1.17
- @atlaskit/pragmatic-drag-and-drop* minor bumps
- @rollup/plugin-inject 5.0.3->5.0.5, @rollup/plugin-wasm 6.1->6.2
- @element-hq/element-call-embedded 0.19.3->0.19.4
- @types/* patches, eslint-plugin-* minors

Breaking change fix:
- immer v11 removed default export; updated 11 files to named import

Temporary: add Sentry test button to WelcomePage for verification.
Remove after confirming errors reach the dashboard.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/pages/client/WelcomePage.tsx

@@ -1,4 +1,5 @@
 import React from 'react';
+import * as Sentry from '@sentry/react';
 import { Box, Button, Icon, Icons, Text, config, toRem } from 'folds';
 import { Page, PageHero, PageHeroSection } from '../../components/page';
 import LotusLogo from '../../../../public/res/Lotus.png';
@@ -63,6 +64,17 @@ export function WelcomePage() {
                     Support
                   </Text>
                 </Button>
+                <Button
+                  onClick={() => {
+                    throw new Error('Sentry test error');
+                  }}
+                  fill="Soft"
+                  before={<Icon size="200" src={Icons.Warning} />}
+                >
+                  <Text as="span" size="B400" truncate>
+                    Test Sentry
+                  </Text>
+                </Button>
               </Box>
             </Box>
           </PageHero>