feat: scaffold CLI project with ClusterClient connection and System.CommandLine

src/ScadaLink.CLI/Program.cs

@@ -0,0 +1,24 @@
+using System.CommandLine;
+using System.CommandLine.Parsing;
+
+var rootCommand = new RootCommand("ScadaLink CLI — manage the ScadaLink SCADA system");
+
+var contactPointsOption = new Option<string>("--contact-points") { Description = "Comma-separated cluster contact points", Recursive = true };
+var usernameOption = new Option<string>("--username") { Description = "LDAP username", Recursive = true };
+var passwordOption = new Option<string>("--password") { Description = "LDAP password", Recursive = true };
+var formatOption = new Option<string>("--format") { Description = "Output format (json or table)", Recursive = true };
+formatOption.DefaultValueFactory = _ => "json";
+
+rootCommand.Add(contactPointsOption);
+rootCommand.Add(usernameOption);
+rootCommand.Add(passwordOption);
+rootCommand.Add(formatOption);
+
+// Placeholder — command groups will be added in Task 6
+rootCommand.SetAction(_ =>
+{
+    Console.WriteLine("Use --help to see available commands.");
+});
+
+var parseResult = CommandLineParser.Parse(rootCommand, args);
+return await parseResult.InvokeAsync();