Prepare ERP source for Gitea deployment

app/core/security/csrf.py

@@ -0,0 +1,16 @@
+import secrets
+from fastapi import Request
+
+CSRF_KEY = "csrf_token"
+
+def get_or_create_csrf_token(request: Request) -> str:
+    token = request.session.get(CSRF_KEY)
+    if not token:
+        token = secrets.token_urlsafe(32)
+        request.session[CSRF_KEY] = token
+    return token
+
+def validate_csrf(request: Request, form_token: str | None) -> None:
+    token = request.session.get(CSRF_KEY)
+    if not token or not form_token or token != form_token:
+        raise PermissionError("CSRF validation failed")