[Bug] Paste Text as single Node

### Bug Description

The pasted lines are still treated as a single text node. This behavior breaks many Rich Text features (e.g., headings or lists) as it affects all the pasted content.

### How to Reproduce

Copy and Paste multi-line or multi-paragraph text into the editor

### Expected Behavior

Each breakline / paragraph treated as new node

### Operating System

MacOS

### AppFlowy Editor Version(s)

6.1.0

### Screenshots

_No response_

### Additional Context

_No response_