Add unit tests for Fuchs_DataService and related components

- Introduced comprehensive unit tests for the Fuchs_DataService library, covering DATEV header formatting, CSV/XML generation, and FdsMfrClient construction.
- Implemented tests for FdsMfr.UpdateNeed parsing and FdsShared utility helpers, ensuring correct functionality and stability.
- Added tests for FdsConfig and FdsMfrClient to validate configuration resolution and client construction.

Document decisions on backend-authoritative invoice and reminder handling

- Created ADR 0008 to clarify that all invoice types and reminder stages are backend-authoritative during drafting and previewing.
- Established that all calculations and settings must be processed server-side, ensuring consistency between online editor and PDF outputs.

Define irreversible mutations for set-price modes in invoices

- Documented ADR 0009 to specify that the "Set mit Preis" and "Nur Set mit Preis" operations are irreversible mutations affecting service request blocks.
- Clarified that these operations are not display toggles but actual data changes, ensuring clear expectations for invoice handling.

Transition MFR ERP sync to in-process execution within the web app

- Created ADR 0010 to outline the migration of Fuchs_DataService from a standalone service to an in-process library within the Fuchs web application.
- Updated configuration and logging management to be handled by the host application, streamlining the sync process.

Add publish profile and periodic hosted service for job scheduling

- Introduced a publish profile for deployment to a specified folder.
- Implemented PeriodicHostedService to manage multiple independent jobs, including the MFR ERP sync, with configurable execution intervals.

Add dotnet-tools.json for EF Core CLI tools

- Included dotnet-tools.json to manage the version of dotnet-ef for Entity Framework Core migrations and commands.

Fuchs/Docs/ARCHITECTURE.md

@@ -12,7 +12,7 @@ The **Fuchs Intranet** solution is a line-of-business web application for **Seba
 | Project | Type | Purpose |
 |---|---|---|
 | **Fuchs** | ASP.NET Core Web (MVC) | Main web application — the intranet |
-| **Fuchs_DataService** | Console / Windows Service (Topshelf) | Background data sync service (MFR ERP polling) |
+| **Fuchs_DataService** | Class Library | MFR ERP sync logic (entity polling, invoice/DATEV files). Hosted in-process by **Fuchs** as a `PeriodicHostedService` (see ADR 0010) — no longer a standalone process. |
 | **MFR_RESTClient** | Class Library | REST/OData client for the MFR ERP system. The REST/OData contract is documented in `MFR_RESTClient/Docs/mfr_interface_description.md`. |
 | **Fuchs_Database** | SSDT (SQL project) | Source of truth for the `fuchs_fds` SQL schema (tables, table types, functions, stored procedures the backend calls). |
 | **OCORE** | Class Library (shared) | Core utilities: SQL, crypto, email, IO, logging |
@@ -96,17 +96,18 @@ The **Fuchs Intranet** solution is a line-of-business web application for **Seba
          │                │
          ▼                ▼
 ┌─────────────────────────────────────────────────────────────────────────┐
-│                    Fuchs_DataService  (Windows Service / Console)        │
+│           Fuchs_DataService  (Class Library, hosted in-process)         │
 │                                                                         │
-│  FdsMain.cs            — Topshelf host, job definitions                 │
-│  PeriodicHostedService — BackgroundService with PeriodicTimer            │
+│  PeriodicHostedService — in Fuchs/Services; BackgroundService +         │
+│                          PeriodicTimer, registered in Program.cs         │
+│                          when Fds:SyncEnabled (ADR 0010)                 │
 │  FdsMfr.cs (IFdsMfr)  — MFR sync orchestration                         │
 │  FdsMfrClient.cs       — MFR REST client wrapper                        │
-│  FdsShared.cs          — FdsConfig (appsettings.json reader)            │
-│  FdsZip.cs             — 7-Zip archive handling (DATEV export)          │
+│  FdsShared.cs          — FdsConfig (reads the host's IConfiguration)    │
+│  (DATEV zip)           — OCORE.zip (System.IO.Compression), no 7-Zip    │
 │  FdsDebug.cs           — Debug/file logging                             │
 │                                                                         │
-│  Jobs:  MfrSync (every N min)                                           │
+│  Jobs:  MfrSync (every Fds:ExecutionFrequency_Minutes)                  │
 │    → UpdateIfNecessary_async  (entity table sync)                       │
 │    → UpdateRequested_async   (on-demand entity refresh)                 │
 │    → GetInvoiceFiles_async   (invoice PDF download)                     │
@@ -176,7 +177,7 @@ Stateless services (`IPdfService`, `IBankingService`, `IMfrClientFactory`) are s
 There is no ORM (no EF Core). All data access uses **ADO.NET via OCORE SQL helpers** (`getSQLDatatable_async`, `getSQLDataSet_async`, `setSQLValue_async`) calling stored procedures and inline SQL. `DataTable`/`DataRow` is the primary data transfer mechanism.
 
 ### 4.5 Background Service
-`Fuchs_DataService` runs as a Windows Service (Topshelf) with a `PeriodicHostedService` that polls the MFR ERP system on a timer, syncing entities and downloading invoice files.
+The MFR ERP sync runs **in-process inside the web app** as a `PeriodicHostedService` (`Fuchs/Services/PeriodicHostedService.cs`), registered in `Program.cs` when `Fds:SyncEnabled` is true. It polls the MFR ERP on a timer (`Fds:ExecutionFrequency_Minutes`), syncing entities and downloading invoice files via the sync logic in the `Fuchs_DataService` library. See ADR [0010](Decisions/0010-mfr-sync-hosted-in-web-app.md).
 
 ### 4.6 Authentication
 Cookie-based authentication (`CookieAuthenticationDefaults`) with custom claims (`FuchsUserIdentity`). SQL-based user/password verification.
@@ -409,7 +410,7 @@ public class MfrClientFactory : IMfrClientFactory, IDisposable
 2. ✅ **Resolved** — `FdsInvoiceData`/`FdsReminderData` are now pure data holders; DB + PDF logic moved to `IInvoiceService`/`IReminderService`.
 3. ✅ **Resolved** — `FdsMfrClient` is created via `IMfrClientFactory` (no `new` in controllers).
 4. ✅ **Resolved** — `OCORE_Charting` is now used (transitively, via `OCORE_web`'s chart engine) by the report renderer (`FuchsVisualization`).
-5. ⏳ **Open** — **Topshelf** in `Fuchs_DataService` could be replaced with native `dotnet` Worker Service hosting for .NET 10 alignment.
+5. ✅ **Resolved** — **Topshelf** removed; `Fuchs_DataService` is now a class library and the MFR sync is hosted in-process by the web app as a `PeriodicHostedService` (ADR 0010).
 
 ---