bcf941dcee
Test matrix restructure: - 256-rank full-system ring runs only ONCE (marked pytest.mark.slow) instead of 7× across matrix + perf tests. Cross-SIP routing is verified by the single run; buffer variants (tcm/hbm/sram) are tested at 8-rank where they finish in <0.5s. - Performance tests use 8-rank instead of 256-rank. - `pytest -m "not slow"` completes in ~2.5min (local dev). - Full suite including slow: ~6min (CI). DataExecutor optimization: - Remove ThreadPoolExecutor from DataExecutor.run(). Same-t_start groups are almost always size 1, so the thread pool creation and dispatch overhead dominated. Simple sequential loop is faster. - Skip dma_read ops at the loop level (they are always no-ops in Phase 2 but were dispatched through _execute_op → _execute_memory). - Remove redundant CLI Phase 2 re-execution: engine._flush_data_phase already replays during engine.wait(); the CLI now only prints the diagnostic summary without re-running DataExecutor. 502 tests pass. Wall time: 25m30s → 5m43s (full), 2m28s (no slow). Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>