feat(glyph): consolidate deckgl Multi layer to defineChart()

Collapse the Multi composer's index.ts + controlPanel.ts into a single
index.tsx. Multi continues to delegate to ../transformProps (the
preset-level transformProps that handles slice composition). The
Multi.tsx component and its imports of each layer's getPoints stay
intact.

This completes the deckgl single-file consolidation: all 10 layers
plus Multi now use defineChart().

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>