feat(ecg): add DICOM ECG waveform extension (#5856)

* feat(ecg): add DICOM ECG waveform extension

Introduce @ohif/extension-dicom-ecg for rendering DICOM waveform (ECG)
data. Register the extension in the basic mode and pluginConfig.json,
and remove ECG from NON_IMAGE_MODALITIES so waveform display sets are
handled by the new viewport.

* refactor(ecg): move ECG support into cornerstone extension per review feedback

- Remove standalone dicom-ecg extension; fold all ECG functionality into
  the cornerstone extension as requested by reviewer
- Add ECG SOP class handler (DicomEcgSopClassHandler) to the cornerstone
  extension getSopClassHandlerModule, registering ECG waveform metadata
  via genericMetadataProvider on display set creation
- Move ECG helpers (buildEcgModule, decodeInt16Multiplex, base64ToArrayBuffer)
  into extensions/cornerstone/src/utils/ecgMetadata.ts
- Handle ECGViewport in CornerstoneViewportService._setDisplaySets by
  detecting ECGViewport instanceof and calling setEcg(imageId) directly,
  so OHIFCornerstoneViewport can be used without a custom ECG viewport component
- Add ECG support to getCornerstoneViewportType utility
- Update basic mode to reference the cornerstone extension's ECG SOP handler
  and use the base cornerstone viewport for ECG display sets
- Migrate ecgMetadata and getCornerstoneViewportType tests

* chore: revert bun.lock to upstream origin/master

---------

Co-authored-by: Bill Wallace <wayfarer3130@gmail.com>

modes/basic/src/index.tsx

@@ -15,7 +15,7 @@ const { structuredCloneWithFunctions } = utils;
  * This list used to include SM, for whole slide imaging, but this is now supported
  * by cornerstone.  Others of these may get added.
  */
-export const NON_IMAGE_MODALITIES = ['ECG', 'SEG', 'RTSTRUCT', 'RTPLAN', 'PR', 'SR'];
+export const NON_IMAGE_MODALITIES = ['SEG', 'RTSTRUCT', 'RTPLAN', 'PR', 'SR'];
 
 export const ohif = {
   layout: '@ohif/extension-default.layoutTemplateModule.viewerLayout',
@@ -47,6 +47,10 @@ export const dicomvideo = {
   viewport: '@ohif/extension-dicom-video.viewportModule.dicom-video',
 };
 
+export const dicomecg = {
+  sopClassHandler: '@ohif/extension-cornerstone.sopClassHandlerModule.DicomEcgSopClassHandler',
+};
+
 export const dicompdf = {
   sopClassHandler: '@ohif/extension-dicom-pdf.sopClassHandlerModule.dicom-pdf',
   viewport: '@ohif/extension-dicom-pdf.viewportModule.dicom-pdf',
@@ -86,6 +90,7 @@ export const extensionDependencies = {
 
 export const sopClassHandlers = [
   dicomvideo.sopClassHandler,
+  dicomecg.sopClassHandler,
   dicomSeg.sopClassHandler,
   dicomPmap.sopClassHandler,
   ohif.sopClassHandler,
@@ -291,6 +296,7 @@ export const basicLayout = {
           ohif.sopClassHandler,
           dicomvideo.sopClassHandler,
           ohif.wsiSopClassHandler,
+          dicomecg.sopClassHandler,
         ],
       },
       {