fix(desktop): drop snapper, which never took a snapshot

The module wrote the configs and the timers, but nothing creates the
.snapshots subvolumes they need, so snapper-timeline failed every hour
with errno:2 and there was never a single snapshot to roll back to.

Removing it rather than fixing it: rollbacks of / are already covered by
NixOS generations, and snapshots of /home would have shared a disk with
/home. That answers "I deleted the wrong file" but not "the disk is
gone", and the second is the failure that actually occurred here.

hosts/desktop/default.nix

@@ -103,28 +103,15 @@
     user = config.moonarch.user;
   };
 
-  # Snapshots of root and home. snap-pac has no counterpart here: NixOS keeps
-  # its own generations, so pre/post package snapshots are redundant. /home is
-  # its own btrfs on the second disk, which snapper does not care about — a
-  # subvolume is a subvolume.
-  services.snapper = {
-    configs = {
-      root = {
-        SUBVOLUME = "/";
-        ALLOW_USERS = [ config.moonarch.user ];
-        TIMELINE_CREATE = true;
-        TIMELINE_CLEANUP = true;
-      };
-      home = {
-        SUBVOLUME = "/home";
-        ALLOW_USERS = [ config.moonarch.user ];
-        TIMELINE_CREATE = true;
-        TIMELINE_CLEANUP = true;
-      };
-    };
-    snapshotInterval = "hourly";
-    cleanupInterval = "1d";
-  };
+  # No snapper here. It was configured for / and /home and never took a single
+  # snapshot: the module writes the configs and the timers, but nobody creates
+  # the .snapshots subvolumes they need, so snapper-timeline failed every hour
+  # with errno:2 for months without anyone noticing. Rather than paper over that,
+  # note what it would and would not have bought: rollbacks of / are already
+  # covered by NixOS generations, and snapshots of /home share a disk with /home,
+  # so they answer "I deleted the wrong file" but not "the disk is gone" — which
+  # is the failure that actually happened here on 09.09.2026. The second question
+  # needs a copy off this machine and is still unanswered.
 
   # No nixos-hardware profile applies to a self-built desktop, so the firmware
   # this machine needs is enabled here instead.