fix(results): encode download filenames (#587)

tests/pages/results.test.ts

@@ -0,0 +1,12 @@
+import { expect, test } from "bun:test";
+import { buildDownloadUrl } from "../../src/helpers/buildDownloadUrl";
+
+test("encodes reserved characters in download filenames", () => {
+  expect(buildDownloadUrl("", "1/2/", "clip #1?.gif")).toBe("/download/1/2/clip%20%231%3F.gif");
+});
+
+test("preserves output path segments while encoding the filename", () => {
+  expect(buildDownloadUrl("/convertx", "user/job/", "報告 100%.pdf")).toBe(
+    "/convertx/download/user/job/%E5%A0%B1%E5%91%8A%20100%25.pdf",
+  );
+});