command: fix s3 panic in filer command (#8208)

command: fix s3 panic in filer command due to uninitialized options

This fixes a nil pointer dereference panic when starting the S3 server
via the `weed filer` command by correctly initializing `iamReadOnly`
and `portIceberg` flags.

Relates to #8200

weed/command/filer.go

@@ -143,6 +143,8 @@ func init() {
 	filerS3Options.concurrentFileUploadLimit = cmdFiler.Flag.Int("s3.concurrentFileUploadLimit", 0, "limit number of concurrent file uploads for S3, 0 means unlimited")
 	filerS3Options.enableIam = cmdFiler.Flag.Bool("s3.iam", true, "enable embedded IAM API on the same S3 port")
 	filerS3Options.cipher = cmdFiler.Flag.Bool("s3.encryptVolumeData", false, "encrypt data on volume servers for S3 uploads")
+	filerS3Options.iamReadOnly = cmdFiler.Flag.Bool("s3.iam.readOnly", true, "disable IAM write operations on this server")
+	filerS3Options.portIceberg = cmdFiler.Flag.Int("s3.port.iceberg", 8181, "Iceberg REST Catalog server listen port (0 to disable)")
 
 	// start webdav on filer
 	filerStartWebDav = cmdFiler.Flag.Bool("webdav", false, "whether to start webdav gateway")