The Homebrew formula is the cli module's product (amy), and the CLI already
owns its packaging artifacts under cli/packaging/ (cli/packaging/macos/
amy.entitlements). The root packaging/ dir was new in this branch and held
nothing else, so co-locate the formula with the module that owns it and drop
the stray root dir. Updates the two BUILDING.md references.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015sso31DfSF9B6EFCVkEqWD
