fix: compute image stats for SEG DICOM files

Changed image-stats to watch activeScalars directly instead of using
useVtkComputed. This ensures stats are computed when SEG images replace
their vtkImageData object after loading, fixing the paint tool error
when selecting segmentation files.

Author: PaulHax

src/components/DicomQuickInfoButton.vue

@@ -92,4 +92,3 @@ const dicomInfo = computed(() => {
 </template>
 
 <style scoped src="@/src/components/styles/utils.css"></style>
-<style scoped></style>

src/store/image-stats.ts

@@ -11,7 +11,6 @@ import {
 import * as Comlink from 'comlink';
 import vtkDataArray from '@kitware/vtk.js/Common/Core/DataArray';
 import vtkImageData from '@kitware/vtk.js/Common/DataModel/ImageData';
-import { useVtkComputed } from '@/src/core/vtk/useVtkComputed';
 import { WLAutoRanges, WL_HIST_BINS } from '@/src/constants';
 import { HistogramWorker } from '@/src/utils/histogram.worker';
 import { Maybe } from '@/src/types';
@@ -134,13 +133,13 @@ export const useImageStatsStore = defineStore('image-stats', () => {
     const activeScalars = computed(() =>
       imageData.value?.getPointData()?.getScalars()
     );
-    const scalarRange = useVtkComputed(activeScalars, () =>
-      activeScalars.value?.getRange(0)
-    );
 
     watch(
-      scalarRange,
-      (range) => {
+      activeScalars,
+      (scalars) => {
+        if (!scalars) return;
+
+        const range = scalars.getRange(0);
         if (range) {
           internalSetScalarRange(id, range[0], range[1]);
         }