Changes

tsk3: Adds `.editorconfig` for consistent code style
This commit adds a new .editorconfig file to ensure consistent
formatting rules across the project. It defines UTF-8 as the charset,
uses LF for line endings, and enforces spaces for indentation. The
configuration disables final newline insertion and trims trailing
whitespace.
For HTML, XHTML, and CSS files, it specifies an indentation size of two
spaces and a maximum line length of 120 characters. This helps maintain
readability and uniform code style across different editors and IDEs.