Bug Report: Accented Characters Are Incorrectly Rendered in Markdown Editor

Version: `ghcr.io/basecamp/writebook:1.2.0`

When using the Markdown editor in WriteBook with the US-International keyboard layout, accented characters are handled incorrectly.

In this keyboard layout, accented characters in Spanish (á, é, í, ó, ú, ü, ñ) are produced using a dead key sequence:

* First press the apostrophe/accent key (')
* Then press the target letter (a) to produce á

If the user wants to type only the apostrophe character itself, they must press:

* apostrophe twice ('')
* or apostrophe followed by space (' )

Current behavior in the WriteBook Markdown editor:

Instead of replacing the dead key sequence with the final accented character, the editor renders both characters together. For example:

* Typing ' followed by a
* Produces: 'á
* Expected result: á

This appears to indicate that the editor is not correctly handling dead key / composition events from international keyboard layouts.