Baseline: Ausgangszustand vor Modularisierung

Erster Commit des bestehenden monolithischen WinForms-Copytraders,
inklusive der Alt-Backups (*.bak), damit diese dauerhaft in der
Historie rekonstruierbar bleiben. Threema-Lib unter libs/ wurde
vendored (nested .git entfernt).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

libs/Threema-MsgApi-Net-Core/README.md

@@ -0,0 +1,19 @@
+# Threema MsgApi .NET Core
+
+This project is a .NET Core fork of the [Threema Message API SDK-NET](https://gateway.threema.ch/en/developer/sdk-net). 
+
+The Threema Message API is an interface that can be used from within customer-specific software to send and receive messages via [Threema Gateway](https://gateway.threema.ch/en).
+
+
+
+### Configuration for Testing
+
+
+Configure in application.json:
+
+- Threema
+  - PrivateKey
+  - ThreemaId
+  - Secret
+- Remove entry "SQLiteConnectionString" or set entry for using public key store.
+