chore(release): HealthChat 1.1.2

Remove the Linux desktop build from the release pipeline. It could never
succeed in this fork: the upstream Linux reusable pulls a build-env Docker
image keyed by the building commit's SHA from the upstream element-hq
registry, where the fork's SHA does not exist, so every tagged build failed
with `manifest unknown`. Desktop releases now ship macOS and Windows only.

- Drop the linux job + its release artifacts from build-healthchat-desktop.yaml
- Bump apps/desktop/package.json to 1.1.2
- Update releasing-healthchat skill + desktop README docs

apps/desktop/package.json

@@ -3,7 +3,7 @@
     "productName": "Element",
     "main": "lib/electron-main.js",
     "exports": "./lib/electron-main.js",
-    "version": "1.1.1",
+    "version": "1.1.2",
     "description": "Element: the future of secure communication",
     "author": {
         "name": "Element",