Polish KarlDNS production UI and docs

router_dyndns/dns/base.py

@@ -9,6 +9,10 @@ class DnsProviderError(RuntimeError):
     """Raised for expected DNS provider publish/delete failures."""
 
 
+class DnsReconciliationError(DnsProviderError):
+    """Raised when provider read-back does not match the requested DNS state."""
+
+
 class DnsConfigurationError(RuntimeError):
     """Raised when DNS provider settings are invalid at startup."""