chore: drop build-ova.sh (Docker build path, superseded by native nix build)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

build-ova.sh

@@ -1,25 +0,0 @@
-#!/usr/bin/env bash
-# Build the VirtualBox OVA inside a throwaway nixos/nix container.
-# No nix needed on the host. Output: ./jupiter.ova
-set -euo pipefail
-
-REPO="$(cd "$(dirname "$0")" && pwd)"
-
-docker run --rm \
-  --device /dev/kvm \
-  --group-add "$(getent group kvm | cut -d: -f3)" \
-  -v "$REPO":/work -w /work \
-  nixos/nix \
-  bash -c '
-    set -euo pipefail
-    git config --global --add safe.directory /work
-    nix build \
-      --extra-experimental-features "nix-command flakes" \
-      .#nixosConfigurations.jupiter-vbox.config.system.build.virtualBoxOVA \
-      -o /tmp/result
-    cp -L /tmp/result/*.ova /work/jupiter.ova
-    chown '"$(id -u):$(id -g)"' /work/jupiter.ova
-    echo "BUILD_DONE"
-  '
-
-echo "OVA: $REPO/jupiter.ova"