Add project files.

Gateway/Controllers/TestController.cs

@@ -0,0 +1,28 @@
+using Gateway.Data;
+using Microsoft.AspNetCore.Mvc;
+
+namespace Gateway.Controllers;
+
+[ApiController]
+[Route("api/test")]
+public class TestController : ControllerBase
+{
+    private readonly SqlService _sql;
+
+    public TestController(SqlService sql)
+    {
+        _sql = sql;
+    }
+
+    [HttpGet("ping")]
+    public async Task<IActionResult> Ping(CancellationToken ct)
+    {
+        // Use a real clientId that exists in tbClient (or you'll hit your FK check)
+        var rqst = """
+        { "clientId":"00000000-0000-0000-0000-000000000001" }
+        """;
+
+        var resp = await _sql.ExecProcAsync("dbo.spTemplate", "ping", rqst, ct: ct);
+        return Content(resp, "application/json");
+    }
+}