chore: upgrade TypeScript 4.9 to 5.9, ESLint 8.29 to 8.57, @typescript-eslint 5 to 7

Resolves all TS2345/TS2347/TS7006 type errors introduced by stricter TypeScript 5.x.
Fix Icons.Settings to Icons.Setting, cast account data returns, fix implicit any.

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

src/app/features/settings/developer-tools/DevelopTools.tsx

@@ -25,7 +25,7 @@ export function DeveloperTools({ requestClose }: DeveloperToolsProps) {
 
   const submitAccountData: AccountDataSubmitCallback = useCallback(
     async (type, content) => {
-      await mx.setAccountData(type, content);
+      await (mx as any).setAccountData(type, content);
     },
     [mx],
   );
@@ -34,7 +34,9 @@ export function DeveloperTools({ requestClose }: DeveloperToolsProps) {
     return (
       <AccountDataEditor
         type={accountDataType ?? undefined}
-        content={accountDataType ? mx.getAccountData(accountDataType)?.getContent() : undefined}
+        content={
+          accountDataType ? (mx as any).getAccountData(accountDataType)?.getContent() : undefined
+        }
         submitChange={submitAccountData}
         requestClose={() => setAccountDataType(undefined)}
       />