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/fis_admin_addGroupMember.sql

@@ -0,0 +1,37 @@
+-- =============================================
+-- Author:		<Author,,Name>
+-- Create date: <Create Date,,>
+-- Description:	<Description,,>
+-- =============================================
+CREATE PROCEDURE [dbo].[fis_admin_addGroupMember]
+	@authaccount varchar(5)
+	,@usergroup_id varchar(5)
+	,@useraccount_id varchar(5)
+AS
+BEGIN
+	SET NOCOUNT ON;
+	DECLARE @utcnow datetime = GETUTCDATE();
+
+    IF NOT EXISTS (SELECT * FROM [dbo].[fis_usergroups_members] WHERE [usergroup_id] = @usergroup_id AND [useraccount_id] = @useraccount_id and [DateDeleted] is null)
+		BEGIN
+
+			INSERT INTO [dbo].[fis_usergroups_members]
+				   ([usergroup_id]
+				   ,[useraccount_id]
+				   ,[UserCreated]
+				   ,[DateCreated]
+				   ,[UserDeleted]
+				   ,[DateDeleted])
+			 VALUES
+				   (@usergroup_id
+				   ,@useraccount_id
+				   ,@authaccount
+				   ,@utcnow 
+				   ,NULL
+				   ,NULL);
+
+		END
+
+	SELECT CAST((CASE WHEN EXISTS (SELECT * FROM [dbo].[fis_usergroups_members] WHERE [usergroup_id] = @usergroup_id AND [useraccount_id] = @useraccount_id and [DateDeleted] is null) THEN 1 ELSE 0 END) as bit);
+
+END