Drops the stylized SVG mark in favor of public/fci-logo.png (the official
Food Co-op Initiative logo, including its wordmark). Because the logo now
contains the 'Food Co-op Initiative' text, the duplicate display-font
wordmark is removed; the 'Co-op Check-in' eyebrow stays as a quiet hairline
divider to the right (sm+ only, hidden on mobile to keep the header tight).