fix(editor): should clear selection when switching doc mode (#11545)

Closes: [BS-3050](https://linear.app/affine-design/issue/BS-3050/切换模式时，清除选区)

blocksuite/affine/shared/src/services/auto-clear-selection-service.ts

@@ -0,0 +1,12 @@
+import { LifeCycleWatcher } from '@blocksuite/std';
+
+// Auto Clear selection when switching doc mode.
+export class AutoClearSelectionService extends LifeCycleWatcher {
+  static override readonly key = 'auto-clear-selection-service';
+
+  override unmounted() {
+    if (this.std.store.readonly) return;
+
+    this.std.selection.clear();
+  }
+}

blocksuite/affine/shared/src/services/index.ts

@@ -1,3 +1,4 @@
+export * from './auto-clear-selection-service';
 export * from './block-meta-service';
 export * from './doc-display-meta-service';
 export * from './doc-mode-service';