users(cassie): add junk dirs to syncthing ignore

Changed files
+2
users
cassie
+2
users/cassie/home/syncthing.nix
···
"(?d)**/node_modules"
"(?d)**/target"
"(?d)**/.svelte-kit"
+
"(?d)**/build"
+
"(?d)**/.gradle"
];
folders = {
"/home/cassie/projects/synced" = {