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

public/theme.js

@@ -72,7 +72,7 @@
     applyTheme(preferredTheme);
 
     // Listen for system preference changes
-    window.matchMedia("(prefers-color-scheme: dark)").addEventListener("change", (e) => {
+    window.matchMedia("(prefers-color-scheme: dark)").addEventListener("change", () => {
       // Only update if no manual preference is set
       if (!localStorage.getItem(THEME_KEY)) {
         applyTheme(null);