First of four family extractions from main.zig. A pure behaviour- preserving move: the eight network and store-transfer handlers -- serve, clone, open, pack, pull, push, sync, remote -- and the helpers private to them move verbatim into src/cmd/sync.zig, byte-identical to their source but for the pub visibility the file boundary forces on the handlers the dispatch switch still calls. Helpers shared with other verbs stay in main.zig, aliased back so the moved bodies read unchanged. No helper is duplicated and no cross-cmd import is created; the test count is unchanged, so nothing was orphaned. main.zig keeps main, the verb dispatch, and the shared helpers. check-in: 47a2717952 user: dmestas tags: trunk