chore(disko): grow swapfile from 20G to 96G

Running strata with qwen3.8-flash-next keeps ~53G of model weights
resident, leaving little RAM for the desktop side and pushing ~13G of
anonymous pages into the 20G swapfile. With swap that full, a burst
risks OOM-killing processes. Disk space is not a constraint (1.9T
btrfs, ~1.4T free), so grow the swapfile to the classic 1x-RAM size.

Keep zram off and zswap at 10%: zram's compressed pool would steal page
cache that the mmap'd weights rely on.

hosts/idols-ai/disko-fs.nix

@@ -108,7 +108,7 @@
                   # Swap subvolume read-only; disko creates swapfile and adds swapDevices
                   "@swap" = {
                     mountpoint = "/swap";
-                    swap.swapfile.size = "20G";
+                    swap.swapfile.size = "96G";
                   };
                 };
               };