refactor: isolate Map Source controls and selection lifecycle

src/sharelink.celestial.test.mjs

@@ -691,6 +691,7 @@ test('visual input listeners are revoked before asynchronous UI teardown', () =>
   const synchronous = disposal.slice(0, firstAwait);
   assert.match(synchronous, /this\._applicationShortcuts\?\.destroy\(\)/);
   assert.match(synchronous, /this\._visualEffects\.stop\(\)/);
+  assert.match(synchronous, /this\._mapSourceControls\?\.destroy\(\)/);
   assert.match(synchronous, /this\._displayControls\?\.destroy\(\)/);
   assert.match(synchronous, /this\._styleParameters\?\.destroy\(\)/);
 });