feat(options): eager startup validation for edge/management options (InboundAPI, ESG, Notification, ManagementService) (arch-review 08 §1.5)

Claude-Session: https://claude.ai/code/session_01MtdgwpEeCUn6cUA5f1LMPj

src/ZB.MOM.WW.ScadaBridge.NotificationService/NotificationOptionsValidator.cs

@@ -0,0 +1,27 @@
+using ZB.MOM.WW.Configuration;
+
+namespace ZB.MOM.WW.ScadaBridge.NotificationService;
+
+/// <summary>
+/// Validates <see cref="NotificationOptions"/> at startup. The values are the SMTP fallback used
+/// by the central Email delivery adapter when the deployed <c>SmtpConfiguration</c> leaves the
+/// corresponding field unset: <see cref="NotificationOptions.ConnectionTimeoutSeconds"/> becomes an
+/// SMTP connect timeout and <see cref="NotificationOptions.MaxConcurrentConnections"/> caps the
+/// connection pool — a non-positive value there is not a usable fallback. Registered with
+/// <c>ValidateOnStart()</c> so a bad <c>ScadaBridge:Notification</c> section fails fast at boot with
+/// a clear, key-naming message.
+/// </summary>
+public sealed class NotificationOptionsValidator : OptionsValidatorBase<NotificationOptions>
+{
+    /// <inheritdoc />
+    protected override void Validate(ValidationBuilder builder, NotificationOptions options)
+    {
+        builder.RequireThat(options.ConnectionTimeoutSeconds > 0,
+            $"ScadaBridge:Notification:ConnectionTimeoutSeconds must be greater than zero " +
+            $"(was {options.ConnectionTimeoutSeconds}); it is the SMTP connect-timeout fallback.");
+
+        builder.RequireThat(options.MaxConcurrentConnections > 0,
+            $"ScadaBridge:Notification:MaxConcurrentConnections must be greater than zero " +
+            $"(was {options.MaxConcurrentConnections}); it caps the SMTP connection pool.");
+    }
+}