dsh-pet-pack: Pet Travel Checklist

# dsh-pet-pack is a “memory”-type plugin for DeepSeek Harness, designed to organize items for pet travel and pet-sitting arrangements. The plugin is implemented entirely in Node and works offline. It uses the `pet_pack` tool to generate a structured travel checklist based on input parameters. Users can install it with the `dsh plugin add github:uckkk/dsh-pet-pack` command and invoke it during a session.