fix: resolve lint issues (XSS K601, knip unused exports, eslint errors)

- Fix XSS warnings in user.tsx by adding safe attribute to elements
- Remove unused exports: ChunkUploadRequest, getArchiveInfo,
  getFileForDirectDownload, createDirectDownloadHeaders, createConverterArchive
- Fix eslint no-unused-vars errors across multiple files
- Fix pdfmathtranslate async Promise executor issue
- Update tests to use toThrow instead of toMatch for Error objects
- Apply prettier formatting

src/components/themeToggle.tsx

@@ -1,7 +1,11 @@
-import { type SupportedLocale, type Translator, createTranslator, defaultLocale } from "../i18n/index";
+import {
+  type SupportedLocale,
+  type Translator,
+  createTranslator,
+  defaultLocale,
+} from "../i18n/index";
 
 export const ThemeToggle = ({
-  locale = defaultLocale,
   t = createTranslator(defaultLocale),
 }: {
   locale?: SupportedLocale;