MEM-019: graf call() early-return skips mmap/handle cleanup (graf/MERGE.c, MAP.c, LOG.c, REBASE.c)

Several graf entry points acquire resources mid-function then reach a call()/bare-return __ that short-circuits past their own cleanup label, leaking already-mapped files, fds, weave mmaps, or an owned graf-open on the error path — violating the acquire-at-top / release-by-owner discipline (CLAUDE.md §5). The goal is to route every failure through the single cleanup path.

Issues

Cleanup label bypassed by early returns.

Blockers

None. Reached on missing inputs / mmap / BASS pressure.

Planned

Single cleanup path per function.