Adds the 4-SIP topology referenced by tests/attention/test_attention_8kv_groups_diag.py
(landed in 39fc2e9). Identical to the repo-root topology.yaml except
``system.sips.count: 2 -> 4``, matching the GQA Llama-70B sharding
study's 1 Q-head-per-cube baseline (64 cubes = 8 KV-groups x 8
cubes/group across 4 SIPs).
Opt-in only — only the diag harness and milestone-gqa-llama70b use
this file via env var. The repo-root topology.yaml is unchanged and
continues to drive milestone-1h-ccl / -gemm at their 2-SIP scale.
Without this commit the diag tests pytest.skip on a fresh checkout
("4-SIP topology missing"). With it, step 1 / step 2 / step 3 all run
and pass.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
