fix(laptop): increase net-vm memory for darp11 storeDisk configs

The `system76-darp11-b-storeDisk` targets were using the default net-vm
memory (512 MiB). With `virtualization.microvm.storeOnDisk = true`, sysvms
boot from EROFS-backed store disks, which increases page-cache/readahead
pressure during early boot.

On darp11 this can starve net-vm memory enough to cause Wi-Fi bring-up
instability (`iwlwifi ... Unable to init nic`) while the system is under
heavy EROFS read activity.

Set a target-specific override:

- `vmConfig.sysvms.netvm.mem = 1024`

for both:
- `system76-darp11-b-storeDisk-debug`
- `system76-darp11-b-storeDisk-release`

This keeps the change scoped to storeDisk variants of this hardware and
avoids altering global installer or base VM defaults.

Signed-off-by: Vunny Sodhi <vunny.sodhi@unikie.com>

Author: vunnyso

targets/laptop/flake-module.nix

@@ -326,6 +326,11 @@ let
           }
         ];
       };
+      vmConfig = {
+        # storeOnDisk enables EROFS-backed stores in sysvms and increases
+        # page-cache/readahead pressure during boot; give net-vm more headroom.
+        sysvms.netvm.mem = 1024;
+      };
     })
 
     (ghaf-configuration {
@@ -578,6 +583,11 @@ let
           }
         ];
       };
+      vmConfig = {
+        # storeOnDisk enables EROFS-backed stores in sysvms and increases
+        # page-cache/readahead pressure during boot; give net-vm more headroom.
+        sysvms.netvm.mem = 1024;
+      };
     })
     # keep-sorted end
   ];