Update to csharp-lsp

{
  "official": [
    {
      "name": "csharp-lsp",
      "author": {
        "name": "Anthropic",
        "email": "support@anthropic.com"
      },
      "source": "./plugins/csharp-lsp",
      "strict": false,
      "version": "1.0.0",
      "category": "development",
      "lspServers": {
        "csharp-ls": {
          "command": "csharp-ls",
          "extensionToLanguage": {
            ".cs": "csharp"
          }
        }
      },
      "description": "C# language server for code intelligence"
    }
  ]
}