[john-endesktop] Update migration plan with completed pre-migration items

machines/john-endesktop/MIGRATION_PLAN.md

@@ -170,6 +170,7 @@ This document outlines the plan to migrate the john-endesktop server from Arch L
    ```bash
    blkid /dev/nvme0n1p5
    # Note the UUID for updating hardware-configuration.nix
+/dev/nvme0n1p5: LABEL="nixos" UUID="5f4ad025-bfab-4aed-a933-6638348059e5" UUID_SUB="4734d820-7b8a-4b7f-853a-026021c1d204" BLOCK_SIZE="4096" TYPE="btrfs" PARTLABEL="data" PARTUUID="9ea025df-cdb7-48fd-b5d4-37cd5d8588eb"
    ```
 
 8. **Copy your NixOS configuration to the server**
@@ -388,11 +389,11 @@ After successful migration and 24-48 hours of stable operation:
 
 Pre-migration:
 - [x] nvme0n1p5 removal from media pool complete
-- [ ] Recent backup verified (< 24 hours)
-- [ ] Maintenance window scheduled
-- [ ] NixOS ISO downloaded
-- [ ] Bootable USB created
-- [ ] NixOS config builds successfully
+- [x] Recent backup verified (< 24 hours)
+- [x] Maintenance window scheduled
+- [x] NixOS ISO downloaded
+- [x] Bootable USB created
+- [x] NixOS config builds successfully
 
 During migration:
 - [ ] ZFS pools exported