Give full tree updates as root message rather than everything as update messages

cista/watching.py

@@ -87,15 +87,7 @@ def format_du():
 
 def format_tree():
     root = tree[""]
-    return msgspec.json.encode(
-        {
-            "update": [
-                UpdateEntry(
-                    key=root.key, size=root.size, mtime=root.mtime, dir=root.dir
-                ),
-            ],
-        },
-    ).decode()
+    return msgspec.json.encode({"root": root}).decode()
 
 
 def walk(path: Path) -> DirEntry | FileEntry | None: