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/image-viewer/ImageViewer.tsx

@@ -7,6 +7,7 @@ import * as css from './ImageViewer.css';
 import { useZoom } from '../../hooks/useZoom';
 import { usePan } from '../../hooks/usePan';
 import { downloadMedia } from '../../utils/matrix';
+import { useMatrixClient } from '../../hooks/useMatrixClient';
 
 export type ImageViewerProps = {
   alt: string;
@@ -16,11 +17,12 @@ export type ImageViewerProps = {
 
 export const ImageViewer = as<'div', ImageViewerProps>(
   ({ className, alt, src, requestClose, ...props }, ref) => {
+    const mx = useMatrixClient();
     const { zoom, zoomIn, zoomOut, setZoom } = useZoom(0.2);
     const { pan, cursor, onMouseDown } = usePan(zoom !== 1);
 
     const handleDownload = async () => {
-      const fileContent = await downloadMedia(src);
+      const fileContent = await downloadMedia(src, mx.getAccessToken());
       FileSaver.saveAs(fileContent, alt);
     };