Fix authenticated media loading for Tauri/WebKit environments

- Add useAuthenticatedMediaUrl hook that fetches media with auth headers
- Add AuthenticatedMedia, AuthenticatedAvatarImage components
- Update downloadMedia and downloadEncryptedMedia to accept access token
- Update all media components to pass access token for auth media
- Fix 401 errors on Matrix servers requiring authenticated media (v1.11+)

This fixes media loading in Tauri desktop apps where service workers
may not work reliably for cross-origin authenticated requests.

src/app/components/message/FileHeader.tsx

@@ -28,9 +28,10 @@ export function FileDownloadButton({ filename, url, mimeType, encInfo }: FileDow
   const [downloadState, download] = useAsyncCallback(
     useCallback(async () => {
       const mediaUrl = mxcUrlToHttp(mx, url, useAuthentication) ?? url;
+      const accessToken = mx.getAccessToken();
       const fileContent = encInfo
-        ? await downloadEncryptedMedia(mediaUrl, (encBuf) => decryptFile(encBuf, mimeType, encInfo))
-        : await downloadMedia(mediaUrl);
+        ? await downloadEncryptedMedia(mediaUrl, (encBuf) => decryptFile(encBuf, mimeType, encInfo), accessToken)
+        : await downloadMedia(mediaUrl, accessToken);
 
       const fileURL = URL.createObjectURL(fileContent);
       FileSaver.saveAs(fileURL, filename);