refactor(web): extract asset viewer logic from Timeline into TimelineAssetViewer component
- Extracted asset viewer navigation and action handling logic from Timeline.svelte into a dedicated TimelineAssetViewer component
- Reduces Timeline.svelte complexity by ~150 lines and improves separation of concerns
- No functional changes - purely a refactoring to improve code organization
## Changes
- Created new TimelineAssetViewer.svelte component containing all asset viewer-related logic
- Moved handlePrevious, handleNext, handleRandom, handleClose, handlePreAction, and handleAction methods
- Timeline.svelte now only passes required props to the new component
- Maintained all existing functionality including navigation, asset actions, and stack management
refactor(web): extract timeline keyboard actions into separate component
Extracts keyboard shortcuts and related functionality from Timeline component into a dedicated TimelineKeyboardActions component for better separation of concerns and maintainability.
