shell: distinguish NotFound from transient errors in provision, use %w wrapping

- s3.user.provision: check gRPC status code on GetUser error — only
  proceed on NotFound, abort on transient/network errors
- s3.iam.import: use %w for error wrapping to preserve error chains,
  wrap PutConfiguration error with context

weed/shell/command_s3_iam_import.go

@@ -58,12 +58,12 @@ func (c *commandS3IAMImport) Do(args []string, commandEnv *CommandEnv, writer io
 
 	data, err := os.ReadFile(*file)
 	if err != nil {
-		return fmt.Errorf("read file: %v", err)
+		return fmt.Errorf("read file: %w", err)
 	}
 
 	config := &iam_pb.S3ApiConfiguration{}
 	if err := filer.ParseS3ConfigurationFromBytes(data, config); err != nil {
-		return fmt.Errorf("parse configuration: %v", err)
+		return fmt.Errorf("parse configuration: %w", err)
 	}
 
 	err = pb.WithGrpcClient(false, 0, func(conn *grpc.ClientConn) error {
@@ -76,7 +76,7 @@ func (c *commandS3IAMImport) Do(args []string, commandEnv *CommandEnv, writer io
 		return err
 	}, commandEnv.option.FilerAddress.ToGrpcAddress(), false, commandEnv.option.GrpcDialOption)
 	if err != nil {
-		return err
+		return fmt.Errorf("put IAM configuration: %w", err)
 	}
 
 	fmt.Fprintf(writer, "Imported IAM configuration from %s\n", *file)

weed/shell/command_s3_user_provision.go

@@ -13,6 +13,8 @@ import (
 	"github.com/seaweedfs/seaweedfs/weed/pb"
 	"github.com/seaweedfs/seaweedfs/weed/pb/iam_pb"
 	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
 )
 
 func init() {
@@ -126,6 +128,8 @@ func (c *commandS3UserProvision) Do(args []string, commandEnv *CommandEnv, write
 		// Step 0: Check if user already exists
 		if resp, getErr := client.GetUser(ctx, &iam_pb.GetUserRequest{Username: *name}); getErr == nil && resp.Identity != nil {
 			return fmt.Errorf("user %q already exists", *name)
+		} else if getErr != nil && status.Code(getErr) != codes.NotFound {
+			return fmt.Errorf("check user existence: %w", getErr)
 		}
 
 		// Step 1: Create policy