Bootstrap CLI package structure for sh1pt

[ralyodio]

Set up the initial CLI package structure for sh1pt as described in the PRD. This includes:

• Creating the packages/cli directory
• Initializing package.json with the correct ESM and bin setup
• Creating bin/sh1pt.js with CLI entrypoint stub
• Creating basic src/ structure for commands and lib modules
• Add minimal scripts (dev, test)
• No TypeScript or extra dependencies for MVP

Reference: #422