Poetry: add header small pattern

[adrianaleites]

• Add spacing sizes to the theme.json as in Twenty Twenty-Four theme.
• Replace spacing with pixels values with spacing presets in header pattern.
• Convert "Food for thoughts" to Heading 1, instead of Paragraph.
• Convert "A collection of valuable thoughts by a very egocentric person." to Site Tagline block, instead of Paragraph.
• Add header small pattern (note: added custom style in theme.json to define the align-items as baseline).
• Replace header in 404, search and archive templates to use instead header small.

Closes #174 Replaces #179