refactor: serve static frontend with Go APIs

tests/auth-login-panel.test.ts

@@ -25,6 +25,8 @@ describe("AuthLoginPanel", () => {
     expect(panelSource).not.toContain('disabled={!configured || submitting || !phone.trim() || !password}');
     expect(panelSource).not.toContain("authMode");
     expect(panelSource).not.toContain("alternateHref");
+    expect(panelSource).toContain("window.location.assign(safeBrowserNext(result.redirectTo, next))");
+    expect(panelSource).not.toContain("window.location.assign(result.redirectTo");
     expect(loginPageSource).not.toContain("/auth/admin-login");
     expect(adminPageSource).toContain("/auth/login");
   });