Codebasis als Dateien ins Arbeitsrepo statt als Gitlink

QuellCode/CentronERP war nur als Gitlink (Submodul-Referenz auf 79c1142)
getrackt, ohne .gitmodules und ohne erreichbares Remote. Der
Untersuchungsgegenstand der Versuchsreihe war damit nicht reproduzierbar
gesichert: Ein Klon haette ein leeres Verzeichnis erhalten, und die Belege
der 3.287 Anforderungen waeren nicht ueberpruefbar gewesen.

Umstellung:
- Historie nach c:\DEV\CentronERP_git_snapshot_79c1142 ausgelagert
  (vollstaendig lesbar, enthaelt 79c1142 und Vorgaenger 89ccfd6)
- Gitlink aus dem Index entfernt
- Dateiinhalt aufgenommen: 24.557 Dateien, rund 333 MB

Die verschachtelte .gitignore der Codebasis gilt weiter, Build-Artefakte
bleiben ausgeschlossen. Details in Versuche/Versuch_01/_Codebasis-Nachweis.md

QuellCode/CentronERP/docs/operations/update-devexpress.md

@@ -0,0 +1,136 @@
+# How to update DevExpress in c-entron<span>.NET
+
+Before your start, **please** talk to everyone who manages one of the other projects (Outlook Add-In, Service-Board, Virtual Mail Assistant, c-entron Agent, etc.) to make sure they can all update as well.
+
+We have documentation for the other projects (even if they have their own wikis) here to consolidate the update process.
+Projects that do not have documentation here are usually updated by their respective developers (ServiceBoard etc.) or have documentation in their git repo.
+
+This'll take you a few hours to complete and you cannot just do it halfway (leaving projects unable to update their c-entron dlls), so make sure to leave enough time and preferably start in the morning.  
+*There __will__ be issues along the way, so be prepared!*
+
+**Please note: this is a very delicate process and needs to be done very thoroughly. You cannot resonably test every project/ui to ensure it's working, so you'll have to make sure you do thing correctly.**  
+**Errors or missing updates will probably only be noticed once people install (even worse if its only noticed once released to customers) and will usually result in bad/cryptic error messages.**  
+**Always check all the changed files in your PRs, make sure everything that needs to be updated is updated and everything that doesnt need to be updated is not updated!**
+
+## Branches & PRs
+
+For consistency reasons it is advisable to use the same pattern of branchname, commitmessage and PR name everywhere.
+ where | pattern | example (for Version 22.1.3)
+--|--|--
+Branch | \<shortsign>/update_devexpress_to_\<versionnumber> | hay/update_devexpress_to_2213
+Commit | Update devexpress to \<versionnumber> | Update devexpress to 22.1.3
+PR | same as the commit message
+
+# [c-entron.Help](https://dev.azure.com/CentronSoftware/c-entron%20Help)
+
+`Solution` > `ContextMenu` > `Manage NuGet Packages for Solution...` to update the NuGet packages.   
+
+ Package|Projects
+ --|--
+`DevExpress.*` | `Centron.Help` 
+
+Update the version number for `Centron.Help` in the `.csproj` file. Put your changes into a PR and self approve and complete it.
+Copy the nuget-package to `/nugets` in c-entron<span>.NET and c-entron Outlook AddIn solution. 
+
+[Reference PR](https://dev.azure.com/CentronSoftware/c-entron%20Help/_git/c-entron%20Help/pullrequest/12178)
+
+
+# [c-entron<span>.NET](https://dev.azure.com/CentronSoftware/c-entron.NET)
+ 
+There are two ways for you to do this, the offical way via nugget packages and the fast way.
+
+ Package|Projects
+ --|--
+`DevExpress.*` | WPF, backend, webservice, shared **and Nexus (Blazor)** — all driven by the `NugetVersionDevExpress` variable (see below), you don't need to touch the individual `.csproj` files
+`Centron.Help` | `Centron.WPF.UI`  
+
+## Updating DevExpress dlls (single source)
+
+The DevExpress version lives in **one** file: **`DevExpress.Version.props`** (repo root), which holds `<NugetVersionDevExpress>`. It is imported by both the root `Directory.Build.props` (WPF/backend/webservice/shared) and `src/nexus/Directory.Build.props` (Nexus/Blazor). Just change the value there — every `DevExpress.*` `PackageReference` uses `Version="$(NugetVersionDevExpress)"`.
+
+> History: Nexus used to hard-code its 6 DevExpress versions in `src/nexus/CentronNexus/CentronNexus.csproj`. Those were switched to `$(NugetVersionDevExpress)` and Nexus's own `Directory.Build.props` imports the shared file (it does not inherit the root props), so a version change is now a single edit.
+
+## Obtaining & updating c-entron.Help (do this FIRST — it is a hard blocker)
+
+`Centron.WPF.UI` references the `Centron.Help` NuGet, and that package is compiled against a specific DevExpress version. If it lags behind, the WPF **markup compiler fails** with `MC1000 … Could not find assembly 'DevExpress.Data.v<OLD>'` — because the new DevExpress ships `DevExpress.Data.v<NEW>` and the old versioned assembly no longer exists.
+
+So **ask the c-entron.Help maintainer for a new `Centron.Help.1.0.xxxx.x.nupkg` built against the new DevExpress version** (see the c-entron.Help section above / its own repo). Then:
+
+1. Copy the new `Centron.Help.1.0.xxxx.x.nupkg` into `/nugets` and delete the old one.
+2. Bump the `Centron.Help` `PackageReference` `Version` in `src/centron/Centron.WPF.UI/Centron.WPF.UI.csproj`.
+3. Clear the old extracted package from the NuGet cache if the version number was reused.
+
+## Running tests
+
+Some EndToEnd expected files contain RTF text with the DevExpress version that generated it, so they must be updated. This is **not just 2 tests** — there are roughly **20+** `*.expected.txt` files under `tests/Centron.Tests.EndToEnd/Tests/Settings/` and `tests/Centron.Tests.EndToEnd/Tests/Helpdesk/`.
+
+You can either run the tests (`HelpdeskSettingsTests` / `SettingsTests`) so they regenerate, or bulk-replace the generator string across all files:
+
+`..{\*\generator DevExpress Office File API/<OLD>.0}..`  
+to   
+`..{\*\generator DevExpress Office File API/<NEW>.0}..`
+
+(e.g. old `25.2.6.0` → new `26.1.3.0`.) These files are UTF-8 **without BOM** and use **CRLF** — preserve both (use `perl -i -pe`, not an editor that rewrites line endings). Ignore the unrelated `9.2.x` strings (that is the c-entron ApplicationVersion) and any `*.actual.txt` (generated, gitignored).
+
+## Breaking changes on major upgrades (e.g. 25.x → 26.x)
+
+A minor bump is usually just the version + heatmaps. A **major** bump additionally tends to need:
+
+- **Clear stale WPF build artifacts.** Delete `**/*_wpftmp.csproj` and the `obj`/`bin` folders of the WPF projects (`Centron.WPF.UI`, `Centron.WPF.UI.Extension`, `Centron.Controls`, `c-entron.misc.ConnectionManager`). They cache the old `DevExpress.*.v<OLD>` reference paths and keep reproducing the `MC1000` error even after the version bump.
+- **Removed/changed API.** Fix compile errors from removed members. Example (26.1): `services.AddDevExpressBlazor(o => o.BootstrapVersion = BootstrapVersion.v5)` — `BootstrapVersion` was removed (Bootstrap 4 dropped, v5 is default) → use plain `services.AddDevExpressBlazor();` in `src/nexus/CentronNexus.Host/Program.cs`.
+- **Version-hashed static assets.** DevExpress 26.1 no longer ships the internal `_content/DevExpress.Blazor/dx-blazor-<hash>.svg` sprite. Any custom `<use href="…#dx-editor-remove-tag">` (e.g. in `EmployeeTreeSelectionDropDown.razor`) breaks — replace with a self-contained inline SVG.
+- Re-verify `wwwroot/css/devexpress-mods.css` overrides and any DevExpress `.Internal` namespace usages.
+- **Restore first** (`dotnet restore Centron.sln`): a failed restore means the DevExpress feed/subscription does not cover the new (major) version — stop and clear that before anything else.
+
+## Updating the heatmaps
+
+The build might fail now, due to the installers not knowing about the new DevExpress DLLs.  
+To fix this, execute the following command line in the root of the git directory:  
+`dotnet run --project .\scripts\Centron.Scripts\Centron.Scripts.csproj -- update-installer-product-heat`  
+This will update the `CentronProductHeat.wxs` and the `WebServiceProductHeat.wxs` (once for c-entron WS) to include the new missing files.  
+*If only the minor version changes the heatmaps might not need an update.*
+
+## Cleanup & PR
+
+Updating the heatmaps re-touches the `Directory.Build.props` file (the `setup-versioning` step rewrites `<Version>` and `<GitCommitId>`). **Revert those two back** (`<Version>1.0.0.0</Version>`, empty `<GitCommitId>`). The DevExpress version itself now lives in `DevExpress.Version.props`, not here, so it is unaffected.
+
+Now you can create the PR and wait for it to merge. Due to the changes to `.sln` and `.csproj` files, it'll need someone from the code-reviewer group.
+
+[Reference PR](https://dev.azure.com/CentronSoftware/c-entron.NET/_git/c-entron.NET/pullrequest/12182)
+
+# [c-entron Outlook AddIn](https://dev.azure.com/CentronSoftware/c-entron%20Outlook%20Add-In)
+
+This only needs to be done in coordination with the maintainer of the Addin.
+
+First you need to update the centron.Help nuget package, then update the packages themselves.   
+
+ Package|Projects
+ --|--
+`DevExpress.*` | `Centron.OutlookAddin` & `Centron.Tickets`
+`Centron.Help` | `Centron.OutlookAddin` & `Centron.Tickets`
+`Centron.Controls` | `Centron.OutlookAddin` & `Centron.Tickets`
+
+As before you also need to update the product heat. (reference c-entron<span>.NET)   
+
+**Make sure to run the terminal as administrator, otherwise the build _will_ fail!**  
+`dotnet run --project .\scripts\Centron.OutlookAddin.Scripts\Centron.OutlookAddin.Scripts.csproj -- update-installer-product-heat`  
+
+[Reference PR](https://dev.azure.com/CentronSoftware/c-entron%20Outlook%20Add-In/_git/c-entron%20Outlook%20Add-In/pullrequest/9193?path=/src/Centron.Tickets/Centron.Tickets.csproj)
+
+# Finishing touches
+
+After you're done you should send a notification e-mail to all developers so they are aware of the update and can (if needed) update their own projects. 
+
+*If you notice any changes to this process, then please update this documentation.*
+
+
+# Further reading
+
+## Error uploading nuget packages
+
+### Error
+`##[error]The nuget command failed with exit code(1) and error(System.AggregateException: One or more errors occurred. ---> System.Net.Http.HttpRequestException: Response status code does not indicate success: 403 (Forbidden - User 'ed8980f1-8a8a-4b5f-a522-5ca37b713bec' lacks permission to complete this action. You need to have 'AddPackage'. (DevOps Activity ID: 36B90B94-83BC-46CE-9349-5A4F110417E5)).`
+
+### Fix
+Ensure the nuget version in the build pipeline via the `NuGetToolInstaller@1` command. [Microsoft documentation](https://docs.microsoft.com/en-us/azure/devops/pipelines/tasks/tool/nuget?view=azure-devops)  
+If you get this error and have no idea what it means go talk to the grandmasters of the build pipelines and show them this