feat(cloud): Add custom cloud API URL configuration support (#181)

* feat(cloud): Add custom cloud API URL configuration support

- Implement RPC methods to set, get, and reset cloud URL
- Update cloud registration to remove hardcoded cloud API URL
- Modify UI to allow configuring custom cloud API URL in developer settings
- Remove environment-specific cloud configuration files
- Simplify cloud URL configuration in UI config

* fix(ui): Update cloud app URL to production environment in device mode

* refactor(ui): Remove SIGNAL_API env & Rename to DEVICE_API to make clear distinction between  CLOUD_API and DEVICE_API.

* feat(ui): Only show Cloud API URL Change on device mode

* fix(cloud): Don't override the CloudURL on deregistration from the cloud.

ui/index.html

@@ -28,7 +28,6 @@
     <title>JetKVM</title>
     <link rel="stylesheet" href="/fonts/fonts.css" />
     <link rel="icon" href="/favicon.png" />
-    %VITE_JETKVM_HEAD%
     <script>
       // Initial theme setup
       document.documentElement.classList.toggle(