Add Marketplace icon; shorten displayName; bump to 1.2.2

- Add top-level PNG icon (media/icon.png) so the Marketplace listing
  renders an icon instead of a broken placeholder (SVG isn't accepted
  for the extension icon).
- Rename displayName to "Simulink Data Explorer".

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: ww-mw

media/icon.png

@@ -1,9 +1,10 @@
 {
   "name": "data-explorer-vscode",
-  "displayName": "Simulink Data Explorer Extension for Visual Studio Code",
+  "displayName": "Simulink Data Explorer",
   "description": "Explore Simulink models, data dictionaries, MAT-files, and projects as interactive tables and relationship trees.",
-  "version": "1.2.1",
+  "version": "1.2.2",
   "publisher": "mathworks",
+  "icon": "media/icon.png",
   "private": true,
   "license": "BSD-3-Clause",
   "repository": {