feat: faster and parallel tests, a remote runner, and a CLAUDE.md hand-off

vmsuite.sh: the ssh-ready snapshot becomes one base image, every block gets a new qcow2 overlay
(no snapshot restore), each suite has its own VM directory and ssh port (2301-2305, boot loaders
2401-2403), the host's package cache is bound over pacman's, VM_MEM defaults to 4G for tests
(run.sh VM_MEM, default 8G). vmtest.sh runs up to MAX_PARALLEL=3 jobs at once, slowest first.
scripts/vmtest-remote.sh runs vmtest.sh on another machine (the PC) over ssh and prints the
summary. CLAUDE.md and the branch cleanup skill now live in the repo.

Not proven as a whole: three VMs at once and the base image work, but a complete parallel run to
the end has not finished yet (P1/P2 in TODO.md); the remote runner and WSL2 are untried (R1-R2).

scripts/vmtest-remote.sh

@@ -0,0 +1,21 @@
+#!/bin/bash
+# Run the whole automated test on another machine (the PC with the VMs) from this one (e.g. a laptop):
+# update the repo there, start scripts/vmtest.sh in a detached `screen`, wait for the summary, print it.
+#   scripts/vmtest-remote.sh <ssh-host> [--no-wait] [vmtest.sh args...]     e.g. scripts/vmtest-remote.sh pc cli hw
+# The branch you are on must be pushed (the remote pulls it). The remote needs this repo, ../steamify-cachyos,
+# ../steammachine-cachyos-live-iso (for the loader list and the ISO), qemu + OVMF + screen, KVM, and the VMs in
+# ~/vms (see the vm-install skill). Env: REMOTE_REPO (default ~/projects/steamify/steamify-cachyos-dev).
+set -uo pipefail
+host="${1:?usage: $0 <ssh-host> [--no-wait] [vmtest.sh args...]}"; shift
+wait=true; args=()
+for a in "$@"; do [[ "$a" == --no-wait ]] && wait=false || args+=("$a"); done
+repo="$(cd "$(dirname "$0")/.." && pwd)"
+branch="$(git -C "$repo" branch --show-current)"
+rr="${REMOTE_REPO:-~/projects/steamify/steamify-cachyos-dev}"
+git -C "$repo" ls-remote --exit-code --heads origin "$branch" >/dev/null 2>&1 || { echo "Push $branch first: the remote pulls it." >&2; exit 1; }
+[[ -z "$(git -C "$repo" status --porcelain)" ]] || echo "Note: uncommitted changes here are NOT tested; the remote runs what is pushed." >&2
+ssh "$host" "rm -f ~/vms/last-test.txt; cd $rr && git fetch -q origin && git checkout -q $branch && git pull -q --ff-only && scripts/vmtest.sh --screen ${args[*]:-}" || exit 1
+$wait || { echo "Started on $host; the summary lands in ~/vms/last-test.txt there (screen -r vmtest to watch)."; exit 0; }
+until ssh "$host" 'grep -q "^== total" ~/vms/last-test.txt 2>/dev/null'; do sleep 30; done
+ssh "$host" 'cat ~/vms/last-test.txt'
+ssh "$host" 'test "$(grep -c "^FAIL" ~/vms/last-test.txt)" -eq 0'