fix: ESLint errors, stale disable comments, bundle splitting

- RoomTimeline.tsx: add eslint-disable comment for intentional eventsLength
  dep on timelineSegments useMemo (needed to detect in-place timeline mutations)
- Remove ~47 stale eslint-disable-next-line comments across 28 files for rules
  that are now off in the flat config (no-param-reassign, jsx-a11y/media-has-caption,
  react/no-array-index-key, etc); run prettier to reformat
- vite.config.js: move manualChunks from rollupOptions.output to
  rolldownOptions.output so Rolldown (Vite 8) actually applies it; main bundle
  drops from 3.5 MB to 814 kB gzip-248 kB, matrix-sdk gets its own 1.16 MB
  cacheable chunk

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

src/app/plugins/call/CallControl.ts

@@ -143,7 +143,6 @@ export class CallControl extends EventEmitter implements CallControlState {
     const callDocument = this.iframe.contentDocument ?? this.iframe.contentWindow?.document;
     if (callDocument) {
       callDocument.querySelectorAll('audio').forEach((el) => {
-        // eslint-disable-next-line no-param-reassign
         el.muted = !sound;
       });
     }

src/app/plugins/call/CallWidgetDriver.ts

@@ -162,10 +162,9 @@ export class CallWidgetDriver extends WidgetDriver {
       // attempt to re-batch these up into a single request
       const invertedContentMap: { [content: string]: { userId: string; deviceId: string }[] } = {};
 
-      // eslint-disable-next-line no-restricted-syntax
       for (const userId of Object.keys(contentMap)) {
         const userContentMap = contentMap[userId];
-        // eslint-disable-next-line no-restricted-syntax
+
         for (const deviceId of Object.keys(userContentMap)) {
           const content = userContentMap[deviceId];
           const stringifiedContent = JSON.stringify(content);

src/app/plugins/react-custom-html-parser.tsx

@@ -1,4 +1,3 @@
-/* eslint-disable jsx-a11y/alt-text */
 import React, {
   type JSX,
   ComponentPropsWithoutRef,