Fix formatting for multi-line command output and delete tasks after completion.

agents/monarch/commands/shell.nim

@@ -1,10 +1,14 @@
-import winim, osproc, strutils
+import winim, osproc, strutils, strformat
 
 import ../types
 
-proc taskShell*(command: seq[string]): TaskResult = 
+proc taskShell*(command: seq[string]): tuple[output: TaskResult, status: TaskStatus] = 
 
-    echo command.join(" ")
-    let (output, status) = execCmdEx(command.join(" ")) 
-    
-    return output 
+    echo "Executing command: ", command.join(" ")
+
+    try: 
+        let (output, status) = execCmdEx(command.join(" ")) 
+        return (output, Completed) 
+
+    except CatchableError as err: 
+        return (fmt"An error occured: {err.msg}" & "\n", Failed)