refactor(tags): use shared card-helpers for peek-card slot construction
Replace innerHTML-based card building in createItemCard with the slot-based
API using shared helpers from app/lib/card-helpers.js. Uses createHeaderSlot,
createFooterSlot, createFaviconEl, and createUrlSpan for consistent card
structure across extensions. Preserves all tags-specific logic including tag
chips, open button, and multi-type item handling.