DP16: add typed get/setAccountData helpers, remove ~19 any-casts

Add centralized typed helpers in src/app/utils/accountData.ts:
- getAccountData<T>(mx, eventType): T | undefined (returns content)
- setAccountData<T>(mx, eventType, content): Promise<void>

These wrap the single `as any` cast needed because matrix-js-sdk's typed
overloads reject the fork's custom account-data event names. Every call site
now stays fully typed on its content shape.

Route all account-data reads/writes that previously used
`(mx as any).getAccountData/setAccountData` or `mx.getAccountData(... as any)`
through the helpers (or, where a MatrixEvent is needed, through the existing
utils/room.ts getAccountData whose param is widened to accept string keys).
No behavior change: same event types, same content shapes.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/features/settings/emojis-stickers/GlobalPacks.tsx

@@ -1,4 +1,4 @@
-import { MatrixEvent, Room } from 'matrix-js-sdk';
+import { Room } from 'matrix-js-sdk';
 import React, { MouseEventHandler, useCallback, useEffect, useMemo, useState } from 'react';
 import {
   Box,
@@ -41,6 +41,7 @@ import {
 import { LineClamp2 } from '../../../styles/Text.css';
 import { allRoomsAtom } from '../../../state/room-list/roomList';
 import { AccountDataEvent } from '../../../../types/matrix/accountData';
+import { getAccountData, setAccountData } from '../../../utils/accountData';
 import { AsyncStatus, useAsyncCallback } from '../../../hooks/useAsyncCallback';
 import { stopPropagation } from '../../../utils/keyboard';
 
@@ -303,9 +304,7 @@ export function GlobalPacks({ onViewPack }: GlobalPacksProps) {
   const [applyState, applyChanges] = useAsyncCallback(
     useCallback(async () => {
       const content =
-        (
-          (mx as any).getAccountData(AccountDataEvent.PoniesEmoteRooms) as MatrixEvent | undefined
-        )?.getContent<EmoteRoomsContent>() ?? {};
+        getAccountData<EmoteRoomsContent>(mx, AccountDataEvent.PoniesEmoteRooms) ?? {};
       const updatedContent: EmoteRoomsContent = JSON.parse(JSON.stringify(content));
 
       selectedPacks.forEach((addr) => {
@@ -322,7 +321,7 @@ export function GlobalPacks({ onViewPack }: GlobalPacksProps) {
         }
       });
 
-      await (mx as any).setAccountData(AccountDataEvent.PoniesEmoteRooms, updatedContent);
+      await setAccountData(mx, AccountDataEvent.PoniesEmoteRooms, updatedContent);
     }, [mx, selectedPacks, removedPacks]),
   );