per-isa-doe.4th: fix PER-ISA-NREPS, make seed/reps VARIABLEs, add common DOE word

PER-ISA-NREPS was 18, inherited unchanged from local master, but every doc
comment (this file's own header, doe_region.h's own design comment) assumes
N=3 reps/cell -- 18 trials/ISA, 54 total across 3 ISAs. With the actual
constant at 18, MU-EXEC-CAMPAIGN's own math (n-reps * MU-N-CFG, MU-N-CFG=6)
produced 108 trials/ISA, 324 total -- well past the DoE region ring's
256-slot ceiling, silently dropping the oldest ~68 records to FIFO eviction
mid-campaign. Confirmed with Captain Bob: 3 is correct. Fixed.

AMD64-SEED/AARCH64-SEED/RISCV64-SEED/PER-ISA-NREPS are now VARIABLEs, not
CONSTANTs, so they're settable before a run instead of fixed at compile time.

New DOE ( seed reps isa-addr isa-u -- ) word: the common interface for
running any named experiment (not just the three fixed per-ISA ones) through
one entry point -- tags, checks resume count, runs the campaign.
RUN-AMD64-CAMPAIGN/RUN-AARCH64-CAMPAIGN/RUN-RISCV64-CAMPAIGN are now thin
wrappers over it, using the stored per-ISA seed/reps variables.

Live-verified on amd64: both capsules load via EXEC with zero errors, and
DOE itself was exercised directly (4567 3 S" doe-xyz" DOE) -- correctly
tagged, correctly checked DOE-RESUME-COUNT, and launched a real campaign
(confirmed by live per-tick physics output and growing trial state; a full
18-trial run takes the ~25-30 min/ISA CLAUDE.md itself documents, so the run
was stopped once the wiring was confirmed working rather than run to
completion for a syntax check).

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

This commit is contained in: