0.18.0: clip instances get stable transform frame + track hide

Each clip instance now renders an invisible frame rect sized to the
union of its layers' footprints across every keyframe. The
transformer wraps that frame so its handles stay on the clip's own
outer constraints instead of chasing the currently-visible inner
shape, and the rect doubles as a hit region so empty-playhead
frames remain selectable. A plain click on a timeline clip-block
also selects the instance (drag still takes over past the 2px
dead-zone).

Clip tracks pick up the same editor-hide affordance as layer
tracks: new eye button on the track-name, setClipTrackEditorHidden
action, and filters in the Konva stackItems + render.ts so
hidden-track instances vanish in the editor. ExportDialog's
skip-hidden opt-in now also strips hidden clip tracks.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

package.json

@@ -1,7 +1,7 @@
 {
   "name": "ruwio",
   "private": true,
-  "version": "0.17.0",
+  "version": "0.18.0",
   "type": "module",
   "scripts": {
     "dev": "vite",