Reports drift between the site's theme overlays and the installed theme.

Usage

mix cherry.theme.diff [TEMPLATE] [--source DIR] [--apply] [--json]

Statuses: current (upstream unchanged), auto_updatable (upstream moved, your copy untouched — --apply re-ejects it with fresh provenance), conflict (both moved; resolve by hand or re-eject with theme.eject --force), untracked (no provenance header), rewritten (a .heex rewrite — owned outright), shadowed (an .eex copy a .heex rewrite outranks). This is the managed-drift answer to silently frozen theme copies.