Second of four family extractions. A pure behaviour-preserving move: the eight working-tree handlers -- add, rm, mv, status, extras, clean, addremove, diff -- and the helpers private to them, including the whole diff-and-compare machinery, move verbatim into src/cmd/tracking.zig, byte-identical to their source but for the pub visibility the dispatch switch forces on the eight handlers. init stays in main.zig because clone bootstraps through it, and stat stays too; both are called by more than this family. Helpers shared with staying verbs stay pub in main.zig, aliased so the moved bodies read unchanged. No helper duplicated, no cross-cmd import created, test count unchanged. check-in: 1df44c39bd user: dmestas tags: trunk