refactor: replace overlay cards with integrated collapsible bars

Changes automation and effects from card-based overlays to integrated bars:
- Automation bar positioned at absolute top with no margins/padding
- Effects bar positioned below automation or at top if automation hidden
- Both bars use bg-card/90 backdrop-blur-sm for subtle transparency
- Collapsible with ChevronDown/ChevronRight indicators
- Close button (X icon) on each bar
- Effects bar dynamically positions based on automation state
- Added effectsExpanded property to Track type
- Removed card container styling for cleaner integration

The bars now sit directly on the waveform as requested, making them feel
more integrated into the track view rather than floating overlays.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

types/track.ts

@@ -34,6 +34,7 @@ export interface Track {
   collapsed: boolean;
   selected: boolean;
   showEffects: boolean; // Show/hide per-track effects panel
+  effectsExpanded?: boolean; // Whether effects bar is expanded (when showEffects is true)
 
   // Selection (for editing operations)
   selection: Selection | null;