DB-3: EF Migrations Drift-Check in CI (has-pending-model-changes)

Nach dem Build-Schritt in test-backend: dotnet-ef 10.0.* global installieren,
dann `dotnet ef migrations has-pending-model-changes` ausführen. Schlaegt fehl
wenn Code-Änderungen an Entities/OnModelCreating keine passende Migration haben.
Fängt genau den Drift, den der SQLite-EnsureCreated-Testhost nicht sieht.

.gitea/workflows/ci.yml

@@ -48,6 +48,19 @@ jobs:
       - name: Build
         run: dotnet build GerbilManager.slnx --no-restore -c Release
 
+      - name: dotnet-ef Tool installieren
+        run: dotnet tool install --global dotnet-ef --version 10.0.*
+
+      - name: DB-3 EF Migrations Drift-Check
+        # Fails CI if the EF model diverges from the snapshot (i.e. a code change touched
+        # entities/OnModelCreating without generating a matching migration). Catches exactly
+        # the class of drift the SQLite/EnsureCreated test host is blind to.
+        run: >
+          dotnet ef migrations has-pending-model-changes
+          --project GerbilManagerWebAPI
+          --startup-project GerbilManagerWebAPI
+          --no-build -c Release
+
       - name: Tests ausfuehren
         run: dotnet test GerbilManager.slnx --no-build -c Release --logger "console;verbosity=normal"