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/inspector/frameSection.ts

@@ -81,7 +81,9 @@ function rectRow(
 ): void {
   const row = createFieldRow(
     host,
-    { key, label, kind: 'number', default: 0, step: 1 },
+    // `decimals: 0` is honest here and only here in the inspector: `normalizeFrameRect` rounds
+    // every value that reaches the model, so the field never shortens a number it is holding.
+    { key, label, kind: 'number', default: 0, step: 1, decimals: 0 },
     value,
     rectHandlers(host, assetId, frameId, key),
   );