chore: scaffold Mudfish VPN decky plugin

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

scripts/test.sh

@@ -0,0 +1,8 @@
+#!/usr/bin/env bash
+# Run the Python unit tests on the Steam Deck (its python3 matches the target runtime closely).
+set -euo pipefail
+cd "$(dirname "$0")/.."
+DECK="${DECK:-deck@192.168.1.50}"
+tar -cf - py_modules tests | ssh "$DECK" '
+  rm -rf /tmp/mfd-test && mkdir /tmp/mfd-test && tar -xf - -C /tmp/mfd-test &&
+  cd /tmp/mfd-test && PYTHONPATH=py_modules python3 -m unittest discover -s tests -t . -v'