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/Tables/fds__payments.sql

@@ -0,0 +1,16 @@
+CREATE TABLE [dbo].[fds__payments] (
+    [Id]               BIGINT          IDENTITY (1, 1) NOT NULL,
+    [ExternalID]       VARCHAR (50)    NULL,
+    [InvId]            VARCHAR (10)    NOT NULL,
+    [CustomerId]       BIGINT          NULL,
+    [DateReceived]     DATETIME        NOT NULL,
+    [AllocationStatus] CHAR (1)        CONSTRAINT [DF_fds__payments_IsAllocated] DEFAULT ((0)) NULL,
+    [IBAN]             VARCHAR (25)    NULL,
+    [sender]           VARCHAR (255)   NULL,
+    [reference]        VARCHAR (35)    NULL,
+    [purpose]          VARCHAR (140)   NULL,
+    [amount]           NUMERIC (10, 3) NOT NULL,
+    [rec_account]      VARCHAR (25)    NULL,
+    CONSTRAINT [PK_fds__payments] PRIMARY KEY CLUSTERED ([Id] ASC)
+);
+