Fix code scanning alert no. 1: DOM text reinterpreted as HTML

[puria]

Fixes https://github.com/ForkbombEu/pqspread/security/code-scanning/1

To fix the problem, we need to ensure that any text content retrieved from the DOM and inserted into the HTML is properly escaped to prevent XSS attacks. The best way to fix this issue is to use a function that escapes HTML special characters before inserting the content into the HTML template.

We will:

1. Create a utility function to escape HTML special characters.
2. Use this function to escape the title, content, and description attributes before inserting them into the HTML template.

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