docs(editor): add doc for reactive types in store (#10958)

blocksuite/docs/api/@blocksuite/store/classes/Boxed.md

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+[**@blocksuite/store**](../../../@blocksuite/store/README.md)
+
+***
+
+[BlockSuite API Documentation](../../../README.md) / [@blocksuite/store](../README.md) / Boxed
+
+# Class: Boxed\<Value\>
+
+Boxed is to store raw data in Yjs.
+By default, store will try to convert a object to a Y.Map.
+If you want to store a raw object for you want to manipulate the Y.Map directly, you can use Boxed.
+
+> [!NOTE]
+> Please notice that the data will be stored in Y.Map anyway so it can not hold data structure like function.
+
+## Example
+
+```ts
+const boxedObject = new Boxed({ a: 1, b: 2 });
+const boxedYMap = new Boxed(new Y.Map());
+boxedObject.getValue().a; // 1
+boxedYMap.getValue().set('a', 1);
+boxedObject.setValue({ foo: 'bar' });
+```
+
+## Type Param
+
+The type of the value stored in the Boxed.
+
+## Type Parameters
+
+### Value
+
+`Value` = `unknown`
+
+## Methods
+
+### getValue()
+
+> **getValue**(): `undefined` \| `Value`
+
+Get the current value of the Boxed.
+
+#### Returns
+
+`undefined` \| `Value`
+
+***
+
+### setValue()
+
+> **setValue**(`value`): `Value`
+
+Replace the current value of the Boxed.
+
+#### Parameters
+
+##### value
+
+`Value`
+
+The new value to set.
+
+#### Returns
+
+`Value`
+
+***
+
+### from()
+
+> `static` **from**\<`Value`\>(`map`): `Boxed`\<`Value`\>
+
+Create a Boxed from a Y.Map.
+It is useful when you sync a Y.Map from remote.
+
+#### Type Parameters
+
+##### Value
+
+`Value`
+
+The type of the value.
+
+#### Parameters
+
+##### map
+
+`YMap`\<`unknown`\>
+
+#### Returns
+
+`Boxed`\<`Value`\>
+
+#### Example
+
+```ts
+const doc1 = new Y.Doc();
+const doc2 = new Y.Doc();
+keepSynced(doc1, doc2);
+
+const data1 = doc1.getMap('data');
+const boxed1 = new Boxed({ a: 1, b: 2 });
+data1.set('boxed', boxed1.yMap);
+
+const data2 = doc2.getMap('data');
+const boxed2 = Boxed.from<{ a: number; b: number }>(data2.get('boxed'));
+```
+
+***
+
+### is()
+
+> `static` **is**(`value`): `value is Boxed<unknown>`
+
+Check if a value is a Boxed.
+
+#### Parameters
+
+##### value
+
+`unknown`
+
+#### Returns
+
+`value is Boxed<unknown>`
+
+#### Example
+
+```ts
+const doc = new Y.Doc();
+
+const data = doc.getMap('data');
+const boxed = new Boxed({ a: 1, b: 2 });
+Boxed.is(boxed); // true
+
+data.set('boxed', boxed.yMap);
+Boxed.is(data.get('boxed)); // true
+```