a8fb1233e3
Update CHECKPOINT-MEM.md to reflect that Steps 1-9 of lets-see-options-for-merry-dijkstra.md are shipped. Notes that ISSUE-MEM-002 is closed in the user-call path (matchContextAllocCall remains as a documented comptime escape hatch), Phase 1.2/1.3/1.4 are unblocked, and points future sessions at the MEM plan (tidy-doodling-cray.md) for the next phase.