Print a failed command's error once on stderr (closes #433)

A command that failed after startup wrote the error twice on stderr:
as an ERROR log record and as the final ERROR: line. The failure
handlers now log the failure at info level, so the record appears only
under --verbose or --debug, next to the records that led up to it.

Model: opus-5-5

internal/cli/remote.go

@@ -98,7 +98,7 @@ func newRemoteInfoCommand() *cobra.Command {
 			}, func(v *vaultik.Vaultik) error {
 				return v.RemoteInfo(jsonOutput)
 			}, func(err error) {
-				log.Error("Failed to get remote info", "error", err)
+				log.Info("Failed to get remote info", "error", err)
 				ReportErrorf("Failed to get remote info: %v", err)
 			})
 		},