Replace empty panels with offline host message for better UX

- Hide all system/backup/service panels when host is offline
- Show centered wake-up message with host status
- Display "Press 'w' to wake up host" if MAC address configured
- Provide clear visual indication when hosts are unreachable
- Improve user experience by removing confusing empty panels

Version 0.1.64

shared/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "cm-dashboard-shared"
-version = "0.1.63"
+version = "0.1.64"
 edition = "2021"
 
 [dependencies]