Add a decimals option, fix dropdown overflow and the texture filter

- NumberField takes a decimals option (default 3); frame rects and the
  slice dialog use 0, matching their integer model.
- Button truncates its label to the drawn width; Dropdown reserves the
  chevron slot. NodeView reuses the shared truncate().
- Setting scaleMode leaves the style's shared resource id in place, so
  the old GPU sampler stayed in use until a reload. Call style.update().
- Graph gets a header bar like the Texture tab: GraphEditor is now the
  frame, the former editor is GraphCanvas. A selection the tab does not
  concern no longer unloads the behavior.
- New e2e step 14 guards text overflow across all widgets.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/editor/Editor.ts

@@ -78,8 +78,8 @@ export class Editor implements PlayHost {
       if (this.play.isPlaying) this.play.stop();
     });
 
-    this.graphEditor.traceProvider = (assetId) => this.play.traceFor(assetId);
-    this.graphEditor.timeProvider = () => this.play.time;
+    this.graphEditor.canvas.traceProvider = (assetId) => this.play.traceFor(assetId);
+    this.graphEditor.canvas.timeProvider = () => this.play.time;
 
     this.toolbar = new Toolbar(state, {
       openProjectMenu: (anchor) => this.projects.openProjectMenu(anchor),