fix SigSelect Jasmine: return test API from IIFE; pend touch specs on desktop

window.SigSelect was being clobbered by the IIFE's undefined return value
(var SigSelect = (function(){...window.SigSelect={...}}()) overwrites window.SigSelect
with undefined). Fixed by using return {} like RoleSelect does.

TouchEvent is not defined in desktop Firefox, so the 5 touch-related specs now
call pending() when the API is absent rather than throwing a ReferenceError.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/static_src/tests/SigSelectSpec.js

@@ -110,7 +110,10 @@ describe("SigSelect", () => {
     // ── Touch: OK btn tap allows synthetic click through ──────────────── //
 
     describe("touch on OK button", () => {
-        beforeEach(() => makeFixture());
+        beforeEach(() => {
+            if (typeof TouchEvent === 'undefined') { pending('TouchEvent unavailable in desktop Firefox'); return; }
+            makeFixture();
+        });
 
         it("touchstart on OK btn does not call preventDefault (allows synthetic click)", () => {
             // First tap the card body to show OK
@@ -142,7 +145,10 @@ describe("SigSelect", () => {
     // ── Touch outside grid dismisses stage (mobile) ───────────────────── //
 
     describe("touch outside grid", () => {
-        beforeEach(() => makeFixture());
+        beforeEach(() => {
+            if (typeof TouchEvent === 'undefined') { pending('TouchEvent unavailable in desktop Firefox'); return; }
+            makeFixture();
+        });
 
         it("dismisses stage preview when touching outside the grid (unfocused state)", () => {
             // Focus a card first
@@ -195,6 +201,7 @@ describe("SigSelect", () => {
         });
 
         it("does not call preventDefault on touchstart while a card is reserved", () => {
+            if (typeof TouchEvent === 'undefined') { pending('TouchEvent unavailable in desktop Firefox'); return; }
             SigSelect._setReservedCardId("99");
             var touchEvent = new TouchEvent("touchstart", {
                 bubbles: true,