fix: ensure partial EC volume moves are reported as failures

Set hasMoved=false when a shard fails to move, even if previous shards
succeeded. This prevents the caller from incorrectly assuming the entire
volume was evacuated, which could lead to data loss if the source server
is decommissioned based on this incorrect status.

weed/shell/command_volume_server_evacuate.go

@@ -239,6 +239,8 @@ func (c *commandVolumeServerEvacuate) moveAwayOneEcVolume(commandEnv *CommandEnv
 				fmt.Fprintf(writer, "no available destination for ec shard %d.%d: %d nodes have no free slots\n",
 					ecShardInfo.Id, shardId, skippedNodes)
 			}
+			// Ensure partial moves are reported as failures to prevent data loss
+			hasMoved = false
 			return
 		}
 	}