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/Functions/fds__getRequestTreeIds.sql

@@ -0,0 +1,18 @@
+-- =============================================
+-- Author:		<Author,,Name>
+-- Create date: <Create Date,,>
+-- Description:	<Description,,>
+-- =============================================
+CREATE FUNCTION [dbo].[fds__getRequestTreeIds]
+(	
+	@srqid bigint
+)
+RETURNS TABLE 
+AS
+RETURN 
+(
+	with sp as (
+		SELECT DISTINCT [parentid] = CASE WHEN ISNULL([parentservicerequestid],0) = 0 THEN [id] ELSE [parentservicerequestid] END FROM [dbo].[mfr__servicerequests] as _s where _s.[Id] = @srqid OR _s.[ParentServiceRequestId] = @srqid
+	)
+	SELECT DISTINCT r.[Id] from [dbo].[mfr__servicerequests] as r JOIN sp on r.[Id] = sp.[parentid] OR r.[ParentServiceRequestId] = sp.[parentid] and ISNULL(sp.parentid,0) > 0
+)