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Claude Opus 4.6 created the initial implementation. I reworked it to conform to our existing code style, and verified the paths are real and correct. I also performed local testing with a few casks and had no issues.

For years we've recommended https://github.com/nrlquaker/homebrew-createzap as the way to create zap stanzas for Homebrew/cask. While this external command has been wonderful, it's always bothered me that we had to point to something external for a required stanza. This PR adds a new generate-zap command, so we can create zap stanzas via our own official tooling.