feat: Versionsanzeige (VERSION-Datei, Footer, /api/version, Image-Tag)

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

finance/app/version.py

@@ -0,0 +1,9 @@
+from pathlib import Path
+
+
+def get_version() -> str:
+    f = Path(__file__).resolve().parent.parent / "VERSION"
+    try:
+        return f.read_text().strip()
+    except OSError:
+        return "0.0.0-dev"