Deck showing `/n/n` in the prose, not good experience

### What happened

### Version

0.0.9

### Platform

macOS

### Which editor's theme

_No response_

### Where deck looked

```text

```

### Did the window close on its own?

```text

```

Reproduce the prose rendering problem on macOS with version 0.0.9, using the attached screenshot as the observed result. Trace the deck's prose display path and verify that the visible output contains the intended line breaks rather than the literal `/n/n` text.

Written by the indexing model from the issue text.