HTML markup is corrupted/not preserved when translating formatted text fields (text_with_summary, text_long)
## Problem/Motivation
When using AI Translate to translate content that contains formatted text fields (`text_with_summary`, `text_long`) with HTML markup (e.g. `<p>`, `<strong>`, `<ul>`, `<a href="...">`, etc.), the translated output does not preserve the original HTML structure. The AI model either strips, alters, or partially reconstructs the HTML tags, resulting in broken or invalid markup stored in the translated field value.
This affects any content type that uses fields with a text format such as "Full HTML" or "Basic HTML" via CKEditor.
## Steps to reproduce
1. Install and configure the `ai_translate` submodule (Drupal AI).
2. Create a content type with a `text_with_summary` or `text_long` field using a text format that allows HTML (e.g. "Full HTML").
3. Create a node with rich HTML content in the body field — e.g. paragraphs, bold text, lists, or links.
4. Navigate to the node's translation tab and trigger an AI translation to any target language.
5. Inspect the translated field value (edit form or database).
## Actual behavior
The HTML markup in the translated field is corrupted: tags may be stripped, improperly nested, partially reproduced as plain text, or the entire value may be returned as plain text without any HTML structure.
issue