v1.8.3 - conflicts as persistent repository data
ADR 0016: merge now persists real conflicts (OBJ_CONFLICT + Meta.HC state) instead of aborting. New: conflicts, resolve <idx> take-ours|take-theirs, merge continue, merge abort. status/check understand in-progress merges. format_version 4. Verified on real QEMU (probe 122) + full regression.