fix: clarify Discord onboarding hint (#1487)

Thanks @kyleok.

Co-authored-by: Ganghyun Kim <58307870+kyleok@users.noreply.github.com>

src/commands/onboard-helpers.test.ts

@@ -27,6 +27,8 @@ afterEach(() => {
 
 describe("openUrl", () => {
   it("quotes URLs on win32 so '&' is not treated as cmd separator", async () => {
+    vi.stubEnv("VITEST", "");
+    vi.stubEnv("NODE_ENV", "");
     const platformSpy = vi.spyOn(process, "platform", "get").mockReturnValue("win32");
 
     const url =