Add Cc (Zusatzempfänger) recipient support for invoice emails

Lets an invoice carry an additional Cc recipient alongside the primary
SendToEmail, sent via the ProcessWeb mailer API. Honors the
Fuchs:Email:OverrideRecipient dev safety net: when the override is
active, Cc is dropped entirely (only the single override inbox is
ever reached), never leaked to it.

- IComService.SendEmailAsync / ProcessWebComService: new optional
  `cc` parameter, included in the mailer payload only when non-empty.
- FdsInvoiceData.RawInvoiceEmailCc + BuildInvoiceParams: reads
  `new.invoiceemailcc`, posts @SendToEmailCc.
- IntranetController.Requests: reads SendToEmailCc from the loaded
  invoice row and passes it through on send/resend.
- Fuchs_Database: SendToEmailCc column on fds__invoices, threaded
  through fds__createInvoice/fds__setInvoice/fds__getInvoice and the
  fds__tt__invoice_base/_core table types.
- fis.req_txt_de.js: "Zusatzempfänger (CC)" field label.
- Tests: ProcessWebComServiceTests (Cc included/omitted/dropped under
  override); SystemStatusServiceTests mocks updated for the new
  IComService.SendEmailAsync parameter.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Fuchs/Services/IComService.cs

@@ -15,9 +15,10 @@ public interface IComService
     /// <param name="email">Recipient email address.</param>
     /// <param name="name">Recipient display name.</param>
     /// <param name="attachments">Optional file attachments (filename → content).</param>
+    /// <param name="cc">Optional Cc recipient (e.g. a customer's "Zusatzempfänger").</param>
     /// <returns><c>true</c> when the email was accepted successfully.</returns>
     Task<bool> SendEmailAsync(string reference, string subject, string html,
-        string email, string name, Dictionary<string, byte[]>? attachments = null);
+        string email, string name, Dictionary<string, byte[]>? attachments = null, string? cc = null);
 
     /// <summary>
     /// Sends an SMS message.

Fuchs/Services/InvoiceService.cs

@@ -135,13 +135,13 @@ public class InvoiceService : IInvoiceService
         var sqlParts = new List<string> { "DECLARE @Id varchar(10);" };
         if (!change)
         {
-            sqlParts.Add("EXECUTE [dbo].[fds__createInvoice] @InvoiceType, @InvoiceTitle, @InvoiceBalance, @InvoiceBalance_net, @InvoiceVAT_net1, @InvoiceVAT_1, @PaymentTerm, @CustomerId, @SendToAddress, @SendToEmail, @ProvisionPeriod, @CustomValues, @authuser, @Id OUTPUT, @SendToAddressJson;");
+            sqlParts.Add("EXECUTE [dbo].[fds__createInvoice] @InvoiceType, @InvoiceTitle, @InvoiceBalance, @InvoiceBalance_net, @InvoiceVAT_net1, @InvoiceVAT_1, @PaymentTerm, @CustomerId, @SendToAddress, @SendToEmail, @SendToEmailCc, @ProvisionPeriod, @CustomValues, @authuser, @Id OUTPUT, @SendToAddressJson;");
             sqlParts.Add("EXECUTE [dbo].[fds__createInvoice_Details] @Id, @InvoiceService_net, @InvoiceService_VAT, @InvoiceOptions, @authuser;");
         }
         else
         {
             pl.Add(SQL_VarChar("@InvId", invId));
-            sqlParts.Add("EXECUTE [dbo].[fds__setInvoice] @InvId, @InvoiceType, @InvoiceTitle, @InvoiceBalance, @InvoiceBalance_net, @InvoiceVAT_net1, @InvoiceVAT_1, @PaymentTerm, @CustomerId, @SendToAddress, @SendToEmail, @ProvisionPeriod, @CustomValues, @authuser, @Id OUTPUT, @SendToAddressJson;");
+            sqlParts.Add("EXECUTE [dbo].[fds__setInvoice] @InvId, @InvoiceType, @InvoiceTitle, @InvoiceBalance, @InvoiceBalance_net, @InvoiceVAT_net1, @InvoiceVAT_1, @PaymentTerm, @CustomerId, @SendToAddress, @SendToEmail, @SendToEmailCc, @ProvisionPeriod, @CustomValues, @authuser, @Id OUTPUT, @SendToAddressJson;");
             sqlParts.Add("EXECUTE [dbo].[fds__createInvoice_Details] @Id, @InvoiceService_net, @InvoiceService_VAT, @InvoiceOptions, @authuser;");
         }
         if (invoice.RawProvisionLocation.Length > 0)

Fuchs/Services/ProcessWebComService.cs

@@ -46,10 +46,11 @@ public class ProcessWebComService : IComService
     }
 
     public async Task<bool> SendEmailAsync(string reference, string subject, string html,
-        string email, string name, Dictionary<string, byte[]>? attachments = null)
+        string email, string name, Dictionary<string, byte[]>? attachments = null, string? cc = null)
     {
         using var act = FuchsTelemetry.StartActivity("email.send");
         act?.SetTag("fuchs.email.ref", reference);
+        cc = string.IsNullOrWhiteSpace(cc) ? null : cc.Trim();
 
         string overrideRecipient = _emailSettings.OverrideRecipient ?? "";
         if (!string.IsNullOrWhiteSpace(overrideRecipient))
@@ -58,12 +59,13 @@ public class ProcessWebComService : IComService
             // redirect every outbound email to a single controlled inbox, so a locally
             // enabled mailer can never reach a real tenant-owner or end-customer.
             _logger.LogWarning(
-                "SendEmailAsync: recipient override active for ref {Reference} – redirecting from '{OriginalEmail}' to '{OverrideRecipient}'",
-                reference, email, overrideRecipient);
+                "SendEmailAsync: recipient override active for ref {Reference} – redirecting from '{OriginalEmail}' (cc='{OriginalCc}') to '{OverrideRecipient}'",
+                reference, email, cc ?? "", overrideRecipient);
             act?.SetTag("fuchs.email.overridden", true);
             act?.SetTag("fuchs.email.original_recipient", email);
             subject = $"[DEV \u2192 {email}] {subject}";
             email = overrideRecipient;
+            cc = null;
         }
 
         if (!IsValidEmail(email))
@@ -111,13 +113,14 @@ public class ProcessWebComService : IComService
             var communication = new
             {
                 to = email,
+                cc,
                 subject,
                 body,
                 attachments = attachmentPayload
             };
 
-            _logger.LogDebug("SendEmailAsync ref={Reference} to={Email} attachments={Count}",
-                reference, email, attachmentPayload.Length);
+            _logger.LogDebug("SendEmailAsync ref={Reference} to={Email} cc={Cc} attachments={Count}",
+                reference, email, cc ?? "", attachmentPayload.Length);
 
             var (ok, status, responseBody) = await PostToApiAsync(reference, "e", communication);
             if (ok)