fix(localrepo): Drop stale packages so update.sh can't re-add them

f06bfd1 and a940d91 removed eternalterminal-client/-server,
illogical-impulse-quickshell-git, meshy-git and pacserve from
packages.x86_64, but their .pkg.tar.zst files stayed in localrepo/ and
in local-aur.db. update.sh appends every localrepo package name back to
the list, which would bring the eternalterminal conflict back, and CI
shipped the conflicting packages into the image's /opt/localrepo.

Remove the files and their repo DB entries, re-sort the vulkan-* lines
in packages.x86_64, and drop the names from README.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages.x86_64

@@ -386,6 +386,9 @@ vim
 virt-manager
 virtualbox-guest-utils-nox
 vpnc
+vulkan-intel
+vulkan-nouveau
+vulkan-radeon
 wallust
 wayland-protocols
 wine
@@ -411,6 +414,3 @@ zen-browser-bin
 zram-generator
 zsh
 zsh-completions
-vulkan-radeon
-vulkan-intel
-vulkan-nouveau