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/string_SplitString_ordered.sql

@@ -0,0 +1,30 @@
+
+CREATE FUNCTION [dbo].[string_SplitString_ordered]
+(
+    	@String VARCHAR(MAX) ,
+    	@Delimiter	VARCHAR(10)
+)
+RETURNS @RetTable TABLE(
+    	String varchar(MAX),
+    	RowNo int
+)
+AS 
+BEGIN
+    DECLARE @i INT ,
+    		@j INT ,
+    		@cnt INT
+    SELECT 	@i = 1
+    SET @cnt = 1
+    WHILE @i <= LEN(@String)
+    BEGIN
+    	SELECT	@j = CHARINDEX(@Delimiter, @String, @i)
+    	IF @j = 0
+    	BEGIN
+    		SELECT	@j = LEN(@String) + 1
+    	END
+    	INSERT INTO @RetTable SELECT SUBSTRING(@String, @i, @j - @i), @cnt
+    	SET @cnt = @cnt + 1
+    	SELECT	@i = @j + LEN(@Delimiter)
+    END
+    RETURN
+END