step 1: store M1 at tier=mid
  M1=0bc09794-45ff-4309-ba53-ac58c1131cf0
settle 3s for post-store
step 2: access M1 (3x to bump counter)
settle 2s for access counter flush
step 3: write 2 sibling memories + consolidate
settle 3s for siblings settle
settle 4s for consolidation index
step 4: promote M1 to tier=long
settle 3s for promote settle
step 5: expire M1 via /api/v1/memories/{id}/forget
settle 3s for forget settle
step 6: archive M1 via POST /api/v1/archive
settle 4s for archive settle
step 7: restore M1
settle 3s for restore settle
step 8: archive again then hard-purge
settle 2s for re-archive settle
settle 3s for purge settle