Add remote AUR test script

scripts/test-aur-remote.sh: SSHes to a remote x86_64 server, spins up
an Arch Docker container, installs btest-rs from AUR, runs TCP + UDP
loopback tests, and cleans up.

Usage: ./scripts/test-aur-remote.sh root@myserver

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

scripts/test-aur-remote.sh

@@ -0,0 +1,70 @@
+#!/usr/bin/env bash
+# Test the AUR package on a remote x86_64 Linux server using Docker.
+#
+# Usage:
+#   ./scripts/test-aur-remote.sh [user@host]
+#
+# If no host is given, runs locally (must be x86_64 Linux with Docker).
+# The script SSHes to the remote, runs an Arch container, installs from AUR,
+# tests loopback, and cleans up.
+set -euo pipefail
+
+REMOTE="${1:-}"
+
+TEST_SCRIPT='
+docker run --rm archlinux:latest bash -c "
+set -euo pipefail
+
+echo \"[1/5] Installing build tools...\"
+pacman -Syu --noconfirm base-devel rustup git sudo >/dev/null 2>&1
+
+echo \"[2/5] Setting up Rust...\"
+rustup default stable >/dev/null 2>&1
+
+echo \"[3/5] Creating build user...\"
+useradd -m builder
+echo \"builder ALL=(ALL) NOPASSWD: ALL\" >> /etc/sudoers
+
+echo \"[4/5] Building btest-rs from AUR...\"
+su builder -c \"
+    cd /tmp
+    git clone https://aur.archlinux.org/btest-rs.git 2>/dev/null
+    cd btest-rs
+    makepkg -si --noconfirm 2>&1 | tail -5
+\"
+
+echo \"\"
+echo \"[5/5] Testing...\"
+echo \"--- Version ---\"
+btest --version
+
+echo \"--- Installed files ---\"
+pacman -Ql btest-rs
+
+echo \"--- Loopback test (TCP, 3s) ---\"
+btest -s -P 19876 &
+sleep 2
+btest -c 127.0.0.1 -P 19876 -r -d 3
+kill %1 2>/dev/null || true
+wait 2>/dev/null || true
+
+echo \"\"
+echo \"--- Loopback test (UDP, 3s) ---\"
+btest -s -P 19877 &
+sleep 2
+btest -c 127.0.0.1 -P 19877 -r -u -d 3
+kill %1 2>/dev/null || true
+wait 2>/dev/null || true
+
+echo \"\"
+echo \"=== ALL TESTS PASSED ===\"
+"
+'
+
+if [ -n "$REMOTE" ]; then
+    echo "=== Testing AUR package on $REMOTE ==="
+    ssh "$REMOTE" "$TEST_SCRIPT"
+else
+    echo "=== Testing AUR package locally ==="
+    eval "$TEST_SCRIPT"
+fi