Add Fuchs_Database SSDT project (schema source of truth)

Adds the SQL Server Data Tools project for the fuchs_fds database — tables,
table types, functions and stored procedures that the backend calls (e.g.
fds__getInvoice, fds__merge_bankingtransactions, fds__tt__bankingtransactions,
fds__admin_getReportCatalog, fis_* auth). Build/model caches (bin, obj,
*.dbmdl, *.jfm, *.user) are git-ignored.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Fuchs_Database/dbo/Stored Procedures/fds__createInvoice_Details.sql

@@ -0,0 +1,38 @@
+-- =============================================
+-- Author:		<Author,,Name>
+-- Create date: <Create Date,,>
+-- Description:	<Description,,>
+-- =============================================
+CREATE PROCEDURE [dbo].[fds__createInvoice_Details]
+	@InvId varchar(10)
+	,@InvoiceService_net numeric(10,2)
+	,@InvoiceService_VAT numeric(10,2)
+	,@InvoiceOptions varchar(50)
+	,@authuser varchar(25)
+AS
+BEGIN
+	SET NOCOUNT ON;
+
+	MERGE [dbo].[fds__invoice_details] AS TARGET
+		USING (VALUES(@InvId,@InvoiceService_net,@InvoiceService_VAT,@InvoiceOptions)) SOURCE ([InvId],[InvoiceService_net],[InvoiceService_VAT],[InvoiceOptions]) ON TARGET.[InvID] = SOURCE.[InvID]
+	WHEN MATCHED THEN
+		UPDATE SET 
+           [InvoiceService_net] = ISNULL(SOURCE.[InvoiceService_net], TARGET.[InvoiceService_net])
+           ,[InvoiceService_VAT] = ISNULL(SOURCE.[InvoiceService_VAT], TARGET.[InvoiceService_VAT])
+		   ,[InvoiceOptions] = ISNULL(SOURCE.[InvoiceOptions], TARGET.[InvoiceOptions])
+	WHEN NOT MATCHED BY TARGET THEN
+		INSERT 
+				([InvId]
+				,[InvoiceService_net]
+				,[InvoiceService_VAT]
+				,[InvoiceOptions])
+		VALUES(
+			SOURCE.[InvId]
+			,SOURCE.[InvoiceService_net]
+			,SOURCE.[InvoiceService_VAT]
+			,SOURCE.[InvoiceOptions]
+		)
+	OUTPUT inserted.*
+	;
+    
+END