feat: Projekt-Geruest finance/ mit Config und Test-Setup

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

finance/tests/test_config.py

@@ -0,0 +1,7 @@
+from app.config import get_settings
+
+
+def test_defaults():
+    s = get_settings()
+    assert s.horizon_days == 548
+    assert s.gui_user == "admin"