updating 15.0-CURRENT from ~ 3 weeks ago to 15.0-AlPHA1

The overall plan is:

1. upgrade only the GENERIC kernel package
2. update the EFI boot loader /boot/efi/EFI/FreeBSD/current.efi in my case
3. reboot
4. upgrade all the remaining base system packages
5. re-bootstrap pkg for the new userland
6. delete all non-base system packages
7. install my minimal useful package list
8. reboot again
9. install all the toys
10. celebrate

In practice I didn't quite follow this recipe, but close enough.

upgrade just the kernel first, and reboot

pkg upgrade -r pkg-base FreeBSD-kernel-generic
Updating pkg-base repository catalogue...
pkg-base repository is up to date.
pkg-base is up to date.
The following 1 package(s) will be affected (of 0 checked):

Installed packages to be UPGRADED:
        FreeBSD-kernel-generic: 15.snap20250610163850 -> 15.0.1.20250906130029 [pkg-base]

Number of packages to be upgraded: 1

The operation will free 5 MiB.
45 MiB to be downloaded.

Proceed with this action? [y/N]: y
[1/1] Fetching FreeBSD-kernel-generic-15.0.1.20250906130029.pkg: 100%   45 MiB   9.4MB/s    00:05
Checking integrity... done (0 conflicting)
[1/1] Upgrading FreeBSD-kernel-generic from 15.snap20250610163850 to 15.0.1.20250906130029...
[1/1] Extracting FreeBSD-kernel-generic-15.0.1.20250906130029: 100%

reboot ok