chore: merge blocksuite source code (#9213)

blocksuite/affine/components/src/context-menu/focusable.ts

@@ -0,0 +1,18 @@
+import { computed } from '@preact/signals-core';
+
+import { MenuItem } from './item.js';
+
+export abstract class MenuFocusable extends MenuItem {
+  isFocused$ = computed(() => this.menu.currentFocused$.value === this);
+
+  override connectedCallback() {
+    super.connectedCallback();
+    this.dataset.focusable = 'true';
+  }
+
+  override focus() {
+    this.menu.focusTo(this);
+  }
+
+  abstract onPressEnter(): void;
+}