Fix text staying blurry on zoom by ensuring the first setZoomBucket call
always applies (PixiJS v8 defaults to auto-resolution which skipped the
initial bucket=1 assignment), listening on both 'moved' and 'zoomed'
viewport events, and tightening bucket thresholds from 6 to 9 levels.
Add TextSharpnessManager for crisp text rendering at all zoom levels:
- Discrete zoom buckets (0.5–3x) avoid texture churn on small zoom changes
- Initial bucket applied to all items on setup and newly created items
via SceneManager.onItemCreated callback (fixes blurry-on-load)
- Visibility check uses getItemWorldBounds for correct grouped item coords
- TextSprite/StickySprite gain setZoomBucket() for resolution control
Remove fontSize +/- controls from contextual toolbar — font size is now
controlled purely through direct manipulation (resize → bake).
Hiren Kangad