Revert "coredesktop-dev skill: qemu-hw-display-virtio-vga and doctor's check"

coredesktop-dev now gives its VMs QEMU's standard VGA, which qemu-base
has, so the extra package and doctor's check are gone.

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

skills/coredesktop-dev-sibling.md

@@ -97,7 +97,6 @@ added later reach existing machines on their next `update`. All are in Arch's
 | `bats` | `make test` (CoreDesktop's tests use plain bats, no helper libraries) |
 | `tea` | Gitea's CLI, for pull requests on gitea.federated.computer |
 | `qemu-base` | The smoketest's virtual machines |
-| `qemu-hw-display-virtio-vga` | The VMs' `-vga virtio` (`qemu-base` leaves it out) |
 | `libisoburn` | `xorriso`, to make the smoketest VM's cloud-init disk |
 
 `make`, `git` and `jq` already come with CoreDesktop. Don't add `shfmt` until
@@ -138,7 +137,7 @@ default answer.
 
 No prompts. It prints what it does and exits non-zero only on real failure:
 
-1. `install_packages shellcheck bats tea qemu-base qemu-hw-display-virtio-vga libisoburn`
+1. `install_packages shellcheck bats tea qemu-base libisoburn`
 2. Make `~/.local/bin/coredesktop-dev` a symlink to `bin/coredesktop-dev` in
    this repo, so each pull updates the command without copying.
 3. If the pre-push hook is installed in the working copy, refresh it from
@@ -153,9 +152,6 @@ Subcommands, each with `--help`. With no subcommand, it prints usage.
 Read-only. It reports each of these as ok or a problem, with the fix:
 
 - shellcheck, bats and tea are installed.
-- QEMU has the `virtio-vga` display (`qemu-system-x86_64 -device help`
-  lists it). It's missing without `qemu-hw-display-virtio-vga`, and the
-  smoketest's VMs then fail to start.
 - The working copy from the settings file exists and is a CoreDesktop clone.
 - **The deployed copy has no local changes** (`git status --porcelain
   --untracked-files=no` is empty). If it has some, list them and point to
@@ -291,8 +287,7 @@ Cases worth a test each:
 - `install.sh` refuses the deployed copy as the working copy, and is safe to
   re-run.
 - `update.sh` doesn't prompt and doesn't re-copy an unchanged hook.
-- `doctor` reports a dirty deployed copy, QEMU without `virtio-vga`, and
-  Flatpak use.
+- `doctor` reports a dirty deployed copy, and reports Flatpak use.
 - `check` lints an untracked script and fails on a shellcheck warning in it.
 - `try` gives the command a private `HOME` and `XDG_RUNTIME_DIR`, no
   `DISPLAY`, and the working copy at `~/.local/share/coredesktop`, and