docs: point remaining src/ui.js references at their owners

The README source tree now lists src/ui/ instead of the removed
src/ui.js. docs/CODE-BOUNDARIES.md names src/ui/applicationShell.js as
the owner of panel layout, persistence and share restoration, and
docs/CURRENT-STATE.md places GLOBAL_POST_DEFAULTS in
src/ui/visualPresets.js. QA script comments and test assertion messages
that still named ui.js are updated the same way.

src/loadingFeedback.test.mjs

@@ -628,7 +628,7 @@ test('the loading ticker never runs hidden and stops after loading and notices s
   // safety-net poll, so its `if (document.hidden) return;` is correct there
   // and must not be confused with this self-stopping ticker's leak.
   const armBody = ui.slice(ui.indexOf('_armLoadingFeedbackTicker() {'));
-  assert.ok(armBody.startsWith('_armLoadingFeedbackTicker() {'), 'ticker function not found in ui.js');
+  assert.ok(armBody.startsWith('_armLoadingFeedbackTicker() {'), 'ticker function not found in the UI shell source');
   const arm = armBody.slice(0, armBody.indexOf('\n  }\n') + 5);
 
   // 1. The ARM guard itself refuses while hidden. Previously the only hidden