eval: fold GEMM/allreduce harnesses into self-contained milestone benches

Move the GEMM + allreduce sweep/render logic out of scripts/ and tests/
into two self-contained eval benches so a user can regenerate every
result + figure with one command:

  kernbench run --bench milestone-1h-gemm   (MILESTONE_FAST=1 reuses JSON)
  kernbench run --bench milestone-1h-ccl

- benches/milestone_1h_{gemm,ccl}.py: single home for each domain; the
  run(torch) entry drives the sweeps and writes figures into
  benches/1H_milestone_output/{gemm,ccl}/ (gitignored), then submits a
  sentinel tensor to satisfy the run_bench contract.
- tests/gemm + tests/sccl helpers and scripts/gemm_sweep.py become thin
  re-export/wrapper shims over the benches (single source preserved); the
  pytest-only param builders + _run_distributed wrapper stay in the shim.
- eval-bench pattern: a bench may drive many configs + build its own
  per-config engines (extends ADR-0045 D5; reverses ADR-0044 D1/D2).

ADR-0054 (EN+KO) records the design; ADR-0043/0044/0045 + CLAUDE.md CLI
Semantics amended; ADR INDEX regenerated. Verified: milestone benches run
clean (ok=True, all artifacts), full suite 67 passed, lang-pairs OK.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitignore

@@ -6,6 +6,9 @@
 # Auto-generated mesh file
 cube_mesh.yaml
 
+# Milestone bench output (regenerable: kernbench run --bench milestone-1h-*)
+src/kernbench/benches/1H_milestone_output/
+
 # Python
 __pycache__/
 *.py[cod]