Checkpoint: paired ACL-TTL overhead measurement, 12/18 cells (2/3)

Cells 10-12 complete and verified (480/480 rows, 16/16 cfg coverage,
zero errors each): amd64/67890 enabled, riscv64/13579 enabled,
riscv64/67890 disabled.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

experiments/bare_metal/runs/acl-ttl-overhead-20260820/timing.csv

@@ -8,3 +8,6 @@ order,arch,seed,acl,start_ts,end_ts,elapsed_s,rows,cfgs_ok,errors
 7,aarch64,13579,enabled,1787264974.177469213,1787265291.239105652,317.062,480,TRUE,0
 8,amd64,13579,disabled,1787265488.338670740,1787265680.056553038,191.718,480,TRUE,0
 9,amd64,12345,disabled,1787265875.831736966,1787266064.967044192,189.135,480,TRUE,0
+10,amd64,67890,enabled,1787266216.072579477,1787266416.714834209,200.642,480,TRUE,0
+11,riscv64,13579,enabled,1787266537.716776416,1787266701.705197579,163.988,480,TRUE,0
+12,riscv64,67890,disabled,1787266808.730892518,1787266975.164517195,166.434,480,TRUE,0