fix(app): appearance modal provider scope, worklist preview persistence, and tag browser label overflow (#6136)

- Insert ServiceProvidersManager providers ahead of the dialog/modal
  providers in App.tsx: modal content renders as a sibling of the
  provider's children, so contexts registered via the manager (e.g.
  ActiveThemeProvider) were out of scope and the appearance modal
  crashed with 'useActiveTheme must be used within an ActiveThemeProvider'.
- Persist the worklist preview panel open/closed state in
  sessionStorage so it survives navigating into a study and back.
- Keep the DICOM tag browser instance number label on one line:
  the words truncate, the (n of total) digits never clip.

extensions/default/src/DicomTagBrowser/DicomTagBrowser.tsx

@@ -165,8 +165,11 @@ const DicomTagBrowser = ({
           </div>
           {shouldShowInstanceList && (
             <div className="mx-auto mt-0.5 flex w-1/4 flex-col">
-              <span className="text-muted-foreground flex h-6 items-center pb-2 text-base">
-                Instance Number ({instanceNumber} of {activeDisplaySet?.images?.length})
+              <span className="text-muted-foreground flex h-6 min-w-0 items-center whitespace-nowrap pb-2 text-base">
+                <span className="truncate">Instance Number</span>
+                <span className="shrink-0">
+                  &nbsp;({instanceNumber} of {activeDisplaySet?.images?.length})
+                </span>
               </span>
               <Slider
                 value={[instanceNumber]}