fix: await params in GET request and update Content-Disposition header for special characters

src/app/api/templates/download/[filename]/route.js

@@ -6,7 +6,8 @@ import db from "@/lib/db";
 
 export async function GET(request, { params }) {
 	try {
-		const { filename } = params;
+		// Await params (Next.js 15+ requirement)
+		const { filename } = await params;
 
 		if (!filename) {
 			return NextResponse.json(
@@ -39,12 +40,16 @@ export async function GET(request, { params }) {
 		// Read file
 		const fileBuffer = await readFile(filePath);
 
+		// Encode filename for Content-Disposition header (RFC 5987)
+		// This handles Polish and other special characters
+		const encodedFilename = encodeURIComponent(template.original_filename);
+
 		// Return file with proper headers
 		const response = new NextResponse(fileBuffer, {
 			status: 200,
 			headers: {
 				"Content-Type": template.mime_type || "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
-				"Content-Disposition": `attachment; filename="${template.original_filename}"`,
+				"Content-Disposition": `attachment; filename*=UTF-8''${encodedFilename}`,
 				"Content-Length": fileBuffer.length.toString(),
 			},
 		});