truly clear selection

the way I built this, selection was sticking around but "cleared".
Instead, we should clear it, which also makes sure that the
API method getSelection() returns nothing in this situtation as well.

src/services/focusBlur.ts

@@ -71,14 +71,14 @@ class Controller_focusBlur extends Controller_exportText {
   };
 
   private handleTextareaFocusStatic = () => {
-    if (!this.cursor.selection || this.cursor.selection.isCleared()) {
+    if (!this.cursor.selection) {
       this.cursor.controller.selectAll();
     }
     this.blurred = false;
   };
 
   private handleTextareaBlurStatic = () => {
-    this.cursor.selection?.clear();
+    this.cursor.clearSelection();
   };
 
   private handleWindowBlur = () => {