Comment indentation shifts

## Steps

1. Visit https://stackblitz.com/edit/vitejs-vite-bcqtrm?file=x-component.ts
1. Note the comment's indentation.
1. Run `npm run format:component`.

## Expected

Comment indentation is unchanged.

## Actual

Comment is partly indented to the left and indents further with each `npm run format:component`. Compare with `npm run format:styles`, which does not use `postcss-lit`.

The issue provides a StackBlitz link with a reproducible example in x-component.ts. Start by examining the postcss-lit plugin's handling of comment indentation in template literals. Compare the behavior of format:component (which uses postcss-lit) with format:styles (which does not). Look at the plugin's source code, likely in src/index.ts or similar, focusing on parsing and re-emission of CSS within template literals. Run the provided example to see the shifting indentation, then write a test to verify the fix.

Scritto dal modello di indicizzazione a partire dal testo della issue.