[Plugin] Add Shopify CLI support

Add enhanced completions for Shopify CLI with caps annotation.

## Features
- [ ] Parse shopify.toml
- [ ] App development commands
- [ ] Theme commands
- [ ] Store commands

## Aliases to Add
- shopify-app-serve
- shopify-app-deploy
- shopify-theme-push
- shopify-theme-pull

## References
- https://shopify.dev/docs/apps/tools/cli

/label enhancement,new-plugin
/milestone v0.3