HAOS: add server name field to config flow

Allows users to specify a custom display name when adding the
integration, replacing the hardcoded "LED Screen Controller" title.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

custom_components/wled_screen_controller/strings.json

@@ -5,10 +5,12 @@
         "title": "Set up LED Screen Controller",
         "description": "Enter the URL and API key for your LED Screen Controller server.",
         "data": {
+          "server_name": "Server Name",
           "server_url": "Server URL",
           "api_key": "API Key"
         },
         "data_description": {
+          "server_name": "Display name for this server in Home Assistant",
           "server_url": "URL of your LED Screen Controller server (e.g., http://192.168.1.100:8080)",
           "api_key": "API key from your server's configuration file"
         }