Fix file downloads for Safari with proper filename handling

Implement browser-specific download methods to ensure files download with correct filenames across all browsers. Safari now uses window.location.href while other browsers use blob URLs. Add Content-Disposition header to proxy endpoint for proper filename preservation.

server/api/files/proxy-download.ts

@@ -41,7 +41,8 @@ export default defineEventHandler(async (event) => {
     
     // Set headers for download
     setHeader(event, 'Content-Type', contentType);
-    setHeader(event, 'Content-Disposition', `attachment; filename="${cleanFileName}"`);
+    // Use both filename and filename* for better compatibility
+    setHeader(event, 'Content-Disposition', `attachment; filename="${cleanFileName}"; filename*=UTF-8''${encodeURIComponent(cleanFileName)}`);
     // Content-Length header is set automatically by Nitro when returning a buffer
     
     // Return the file buffer