refactor: separate application shell state and lifecycle owners

src/reasonableDefaults.test.mjs

@@ -253,8 +253,9 @@ test('detection-on-by-default is a default, not an operator override', () => {
   const displayActions = uiSource.slice(uiSource.indexOf('this._displayControls ='));
   const detectionButton = displayActions.slice(displayActions.indexOf('cycleDetection:'), displayActions.indexOf('toggleModels:'));
   assert.match(detectionButton, /cycleDetectionMode\(\)/, 'the button still invokes the detection action');
-  assert.match(detectionButton, /this\._detectionUserOverridden = true;/,
+  assert.match(detectionButton, /this\.claimDetection\(\);/,
     'and the detection control still claims the override when the operator uses it');
+  assert.match(uiSource, /claimDetection: \(\) => \{\s*this\._visualSettings\._detectionUserOverridden = true;/);
 
   // Style-switch semantics are unchanged: Normal is still not a preset owner,
   // so switching TO Normal does not re-apply or clear anything.