fix(groups): unify card styling and fix keyboard navigation
- Use shared peek-card styling for both group and address cards
- Reduce padding (12px) and max-width (300px) for compact layout
- Simplify address cards to match group card structure (header + footer only)
- Remove URL display, show visit count in footer instead
- Fix keyboard navigation focus detection for peek-input shadow DOM
- Fix selected card focus for Enter key support
- Remove manual grid/card CSS in favor of peek-grid/peek-card defaults