feat: add size limit for root tmpfs

hosts/12kingdoms-shoukei/hardware-configuration.nix

@@ -100,6 +100,7 @@ in
     # set mode to 755, otherwise systemd will set it to 777, which cause problems.
     # relatime: Update inode access times relative to modify or change time.
     options = [
+      "size=4G"
       "relatime"
       "mode=755"
     ];

hosts/idols-ai/disko-fs.nix

@@ -17,6 +17,7 @@
     nodev."/" = {
       fsType = "tmpfs";
       mountOptions = [
+        "size=4G"
         "relatime" # Update inode access times relative to modify/change time
         "mode=755"
       ];