feat(pagestream): transparent bg, card sizing, shared navbar component
- Extract page host navbar into reusable peek-navbar web component
(app/components/peek-navbar.js) with URL input, back/forward/reload
buttons, keyboard shortcuts (Cmd+L, Cmd+R, Cmd+[/]), and events
- Update page host (app/page/) to use peek-navbar component, preserving
existing drag/resize/hover trigger zone architecture
- Add peek-navbar to pagestream replacing the old peek-input URL bar
- Pagestream window now opens with transparent: true background
- CSS updated for translucent card backgrounds with backdrop-filter blur
- Active/focused card displayed at ~2x size (scale 1.15 + larger text/icons),
non-active cards scaled down to 0.88 with reduced opacity
- Card gap increased from 8px to 20px for better visual separation
- Navbar URL input auto-focuses when pagestream window opens
- peek-navbar shortcuts property allows host to control keyboard handling