feat(editor): replace slot with rxjs subject (#10768)

blocksuite/affine/model/package.json

@@ -21,6 +21,7 @@
     "@types/lodash-es": "^4.17.12",
     "fractional-indexing": "^3.2.0",
     "lodash-es": "^4.17.21",
+    "rxjs": "^7.8.1",
     "yjs": "^13.6.21",
     "zod": "^3.23.8"
   },

blocksuite/affine/model/src/blocks/root/root-block-model.ts

@@ -12,8 +12,9 @@ export type RootBlockProps = {
 export class RootBlockModel extends BlockModel<RootBlockProps> {
   constructor() {
     super();
-    this.created.once(() => {
-      this.doc.slots.rootAdded.on(id => {
+    const createdSubscription = this.created.subscribe(() => {
+      createdSubscription.unsubscribe();
+      this.doc.slots.rootAdded.subscribe(id => {
         const model = this.doc.getBlockById(id);
         if (model instanceof RootBlockModel) {
           const newDocMeta = this.doc.workspace.meta.getDocMeta(model.doc.id);