fix(#366): skip redundant REST call on tab switch-back (#411)

Prevents the 404 error banner that briefly flashes when switching back
to the Chat tab. The WebSocket keeps the UI current, so the REST call
is only needed on initial session load.

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

app/src/main/java/com/m57/hermescontrol/ui/chat/ChatViewModel.kt

@@ -773,6 +773,11 @@ class ChatViewModel(
     fun refreshCurrentSession() {
         val sessionId = _uiState.value.currentSessionId ?: return
         loadCachedMessages(sessionId)
+        // Skip the REST call if we already have messages — the WebSocket keeps
+        // the UI current. The REST endpoint can 404 on tab switch-back when the
+        // WS session ID doesn't round-trip through the resolver (issue #366),
+        // showing a misleading error banner while the connection is fine.
+        if (_uiState.value.messages.isNotEmpty()) return
         loadSessionMessages(sessionId)
     }