Comment on: v0.4+ candidate: live-fork via memfd-backed source RAM + uffd_wp (deferred from v0.3)

Draft RFC + implementation plan now live: #156 8-week phased plan: PoC → integrate into `forkd-uffd` → pause-window bench → hardening (write-heavy / NUMA / pre-5.7 fallback) → launch. Target: BRANCH pause < 10 ms by removing the synchronous memory write entirely. Switch source RAM to memfd, arm `UFFDIO_WRITEPROTECT`, async dirty-page copier on uffd handler. Comments / prior-art pointers especially welcome on the open questions in the doc — particularly the behavior of `UFFD_WP` on memfd-backed VMAs under `KVM_RUN`.