chore(desktop): brand About panel, author, homepage, and description as HealthChat

- author.name → HealthChat so the macOS About panel copyright reads
  "Copyright © 2026 HealthChat" (electron-builder derives copyright from author.name)
- author.email → support@healthchat.ch
- homepage → https://www.healthchat.ch
- app description (de-CH) → "Die sichere Chat-Lösung für Schweizer HealthProfessionals"

apps/desktop/package.json

@@ -6,10 +6,10 @@
     "version": "1.2.3",
     "description": "Element: the future of secure communication",
     "author": {
-        "name": "Element",
-        "email": "support@element.io"
+        "name": "HealthChat",
+        "email": "support@healthchat.ch"
     },
-    "homepage": "https://element.io",
+    "homepage": "https://www.healthchat.ch",
     "repository": {
         "type": "git",
         "url": "https://github.com/vector-im/element-web"