Checkpoint: paired ACL-TTL overhead measurement, 3/18 cells

In-progress paired ACL-enabled/disabled campaign (18 cells: 3 seeds x 3
ISAs x 2 ACL states, randomized order, one continuous sitting per
Section O's naming/scoping ruling -- calling this "ACL-TTL overhead",
not "ACL-RWT", since the RWT mechanism no longer exists in the codebase).

Real finding along the way, not blocking: capsules/zuse.4th's
ACL-ZUSE-BOOT places its own self-pin inside its own colon-definition
body instead of after the closing ";", causing a genuine forward-
reference failure at capsule-load time. Confirmed via live VM state
query (EXEC's ACL-MODE@/ACL-PINNED? and DOE-WORK's ACL-MODE@) that this
does NOT affect the core ACL enforcement mechanism itself --
ACL-INIT-PRIMITIVES correctly stamps the whole dictionary, ACL-BOOT
correctly pins EXEC/BYE to STRICT -- so it doesn't invalidate this
measurement. Not fixed, flagged only.

3 cells complete and verified (480/480 rows, 16/16 cfg coverage, zero
errors each): riscv64/12345 disabled+enabled, aarch64/13579 disabled.
Cell 3's timing is mtime-based/approximate rather than precise
wall-clock -- a multi-hour session gap landed inside its measurement
window, contaminating the direct stopwatch reading; the log file's own
last-write mtime is used as a corrected proxy instead, noted as such in
timing.csv.

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

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

@@ -0,0 +1,4 @@
+order,arch,seed,acl,start_ts,end_ts,elapsed_s,rows,cfgs_ok,errors
+1,riscv64,12345,disabled,1787246865.003797220,1787247037.443151234,172.439,480,TRUE,0
+2,riscv64,12345,enabled,1787247549.357850085,1787247707.475092723,158.117,480,TRUE,0
+3,aarch64,13579,disabled,1787248108.701960810,1787248383,274.298,480,TRUE,0