fix(#72): echo server's WebSocket close code instead of hardcoded 1000

* ci: prevent concurrency cancellation on rapid main merges

The concurrency group used github.ref which is static for main
(refs/heads/main). When multiple PRs merged rapidly (~2 min apart),
each merge commit cancelled the previous CI run before it could finish.

Fix: use github.sha for push events to main (unique per commit) while
keeping the ref-based group for PR branches (cancels on new commits to
the same PR branch).

* refactor(#82): remove dead SkeletonList/SkeletonCard composables

* fix(#72): echo server's WebSocket close code instead of hardcoded 1000

---------

Co-authored-by: ronia <ronia@m57>
Co-authored-by: M57 <hy4ri@users.noreply.github.com>

app/src/main/java/com/m57/hermescontrol/data/ws/HermesWsClient.kt

@@ -253,7 +253,7 @@ object HermesWsClient {
             reason: String,
         ) {
             Log.d(TAG, "WebSocket closing: $code $reason")
-            ws.close(1000, null)
+            ws.close(code, reason)
         }
 
         override fun onClosed(