Replace munki-pkg with swiftpkg for managed Python packaging

Objective

Migrate this repository's managed Python installer packaging to codecarton/swiftpkg and retire the munki-pkg build dependency.

Current behavior

build_python_framework_pkgs.zsh downloads a pinned munki-pkg commit using MP_SHA, MP_BINDIR, and MP_ZIP. Its build_pkg() function generates recommended/build-info.json, stages preinstall-cleanup, invokes munkipkg, and moves the signed package into outputs/. Notarization and stapling run separately. Without an installer identity, the script skips package creation and still produces the framework ZIP.

Implementation scope

• Select and pin a published swiftpkg CLI release compatible with Apple Silicon build hosts; verify the downloaded artifact against a pinned SHA-256 and document prerequisites.
• Replace the munki-pkg download, temporary paths, and invocation with swiftpkg; propagate failures clearly.
• Validate compatibility of every generated build-info setting, especially ownership, suppress_bundle_relocation, preserve_xattr, distribution_style, and signing_info. Implement equivalent behavior for any unsupported settings.
• Preserve the package identifier (io.macadmins.python.recommended), version derivation, output filename/location, payload layout, permissions, symlinks, extended attributes, and preinstall cleanup behavior.
• Preserve framework code signing and the existing installer signing/notarization/stapling sequence; avoid duplicate notarization.
• Ensure Python 3.11, 3.12, 3.13, and 3.14 workflows use the replacement and continue publishing expected artifacts; update workflows only where necessary.
• Update README build prerequisites and credits. Remove active munki-pkg dependencies and obsolete bootstrap references while retaining appropriate historical attribution.

Acceptance criteria

• Local and CI packaging use the pinned swiftpkg CLI with verified artifact integrity; no active build path downloads or executes munki-pkg.
• All generated build-info options have verified equivalent behavior, with any migration differences documented.
• On Apple Silicon, inspect a baseline munki-pkg package and replacement package to confirm equivalent receipts, version, install paths, payload, ownership/modes, symlinks, extended attributes, installer scripts, and non-relocation behavior.
• Signed packages pass signature checks, notarization, and stapling validation using the existing signing credentials.
• Clean-install and upgrade smoke tests on a disposable Apple Silicon Mac confirm preinstall cleanup, framework installation at /Library/ManagedFrameworks/Python/Python3.framework, the managed_python3 symlink, and execution/imports of the managed runtime and bundled dependencies.
• The no-installer-identity path continues producing the framework ZIP without requiring signing credentials.
• Each supported Python workflow builds and publishes the expected package artifact.
• zsh -n build_python_framework_pkgs.zsh passes; any modified workflow YAML parses successfully.
• README documents the replacement tool, pinned version/update procedure, and prerequisites.

Boundaries

This change replaces the package builder. It does not remove support for deploying the resulting installer through Munki, change Python/runtime dependencies, add the Swiftpkgr desktop app, or change the managed framework's installation contract.

Commencez par build_python_framework_pkgs.zsh, en particulier par build_pkg(), les variables d’amorçage de munki-pkg et la génération existante de build-info.json. Examinez ensuite les fichiers de workflow pour Python 3.11–3.14 et les prérequis du README. Comparez les packages de référence et de remplacement sur Apple Silicon, et utilisez les vérifications répertoriées du shell, de la signature, de la notarisation, des smoke tests et des artefacts pour vérifier que le travail est terminé.