Move the display toggles into a fixed footer…

Details

Build on the v3 branch. The three display controls (cursor gravity, weather,
brightness) move out of the floating bottom-right stack into a new fixed
bottom bar that mirrors the top nav:
- Symmetric to the header: same glass material + blur, same height
  (--v3-nav-h: 62px desktop / 72px mobile shared with the nav), and a mirrored
  TOP divider that appears while content is behind it and drops flush at the
  very bottom (mirror of the nav's is-scrolled bottom divider).
- Edge-anchored mono eyebrows ("Display" / "Controls") frame the toggles,
  which sit dead-centre via a 1fr auto 1fr grid, so the dock reads as a matched
  pair to the nav rather than three buttons in a void.
- The hover/focus pill-expand is now contained in the bar: each toggle sits in
  a fixed-width slot and expands left into the gap, so the icon centres never
  shift on hover.
- Slightly denser fill than the nav (0.86 dark / 0.9 light) so the busy stat
  wall / content footer behind the dock stays frosted rather than legible.
- Static/fixed: stays pinned while scrolling; the body reserves bottom space so
  the content footer clears it.
Mobile drops the framing labels and tightens the toggles into a centred trio;
the bar falls back to an opaque colour where backdrop-filter is unsupported.
Button ids are unchanged, so the effect scripts and the command palette keep
working.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016HyukoK8KXyZw4hY9Wm3zN

Files changed (10)