fix(cover): preserve spaces in 'npm i ahize' tspan

rsvg-convert was collapsing the leading/trailing whitespace inside the
<tspan> separating the package name from 'i', so the rendered PNG read
'npm iahize'. Use xml:space="preserve" + non-breaking spaces so every
renderer keeps the gap.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: productdevbook