feat: add GrpcPort config to NodeOptions with startup validation

src/ScadaLink.Host/NodeOptions.cs

@@ -6,4 +6,5 @@ public class NodeOptions
     public string NodeHostname { get; set; } = string.Empty;
     public string? SiteId { get; set; }
     public int RemotingPort { get; set; } = 8081;
+    public int GrpcPort { get; set; } = 8083;
 }

src/ScadaLink.Host/StartupValidator.cs

@@ -42,6 +42,10 @@ public static class StartupValidator
 
         if (role == "Site")
         {
+            var grpcPortStr = nodeSection["GrpcPort"];
+            if (grpcPortStr != null && (!int.TryParse(grpcPortStr, out var gp) || gp < 1 || gp > 65535))
+                errors.Add("ScadaLink:Node:GrpcPort must be 1-65535");
+
             var dbSection = configuration.GetSection("ScadaLink:Database");
             if (string.IsNullOrEmpty(dbSection["SiteDbPath"]))
                 errors.Add("ScadaLink:Database:SiteDbPath required for Site nodes");

src/ScadaLink.Host/appsettings.Site.json

@@ -4,7 +4,8 @@
       "Role": "Site",
       "NodeHostname": "localhost",
       "SiteId": "site-a",
-      "RemotingPort": 8082
+      "RemotingPort": 8082,
+      "GrpcPort": 8083
     },
     "Cluster": {
       "SeedNodes": [

tests/ScadaLink.Host.Tests/StartupValidatorTests.cs

@@ -217,6 +217,43 @@ public class StartupValidatorTests
         Assert.Contains("SeedNodes must have at least 2 entries", ex.Message);
     }
 
+    [Theory]
+    [InlineData("0")]
+    [InlineData("-1")]
+    [InlineData("65536")]
+    [InlineData("abc")]
+    public void Site_InvalidGrpcPort_FailsValidation(string grpcPort)
+    {
+        var values = ValidSiteConfig();
+        values["ScadaLink:Node:GrpcPort"] = grpcPort;
+        var config = BuildConfig(values);
+
+        var ex = Assert.Throws<InvalidOperationException>(() => StartupValidator.Validate(config));
+        Assert.Contains("GrpcPort must be 1-65535", ex.Message);
+    }
+
+    [Fact]
+    public void Site_ValidGrpcPort_PassesValidation()
+    {
+        var values = ValidSiteConfig();
+        values["ScadaLink:Node:GrpcPort"] = "8083";
+        var config = BuildConfig(values);
+
+        var ex = Record.Exception(() => StartupValidator.Validate(config));
+        Assert.Null(ex);
+    }
+
+    [Fact]
+    public void Central_InvalidGrpcPort_NotValidated()
+    {
+        var values = ValidCentralConfig();
+        values["ScadaLink:Node:GrpcPort"] = "0";
+        var config = BuildConfig(values);
+
+        var ex = Record.Exception(() => StartupValidator.Validate(config));
+        Assert.Null(ex);
+    }
+
     [Fact]
     public void MultipleErrors_AllReported()
     {