Consolidate ICE operations and add UNITE 42:1 ablation

[ElmoPA]

Summary

• consolidate the reusable ICE launcher, requeue, strict checkpoint validation, and multi-node archive infrastructure from PRs feat(ice): add validated Planar BC tooling #4, Add fail-closed UNITE ICE continuation tooling #5, and Harden ICE clean DP campaign launch contract #6 onto current main
• preserve clean standard-DP campaign tooling and current UNITE validation/telemetry
• enforce one GPU with an H100|H200 constraint for UNITE
• remove ~7.6k lines of historical cross-cluster cutover/staging machinery
• add an explicit N=8 UNITE 42:1 flow-sample ablation while preserving every 14:1 row
• keep PipelineAlgo fully route/domain agnostic; UNITE diagnostics remain in the UNITE wrapper

Verification

• 340 passed full repository test suite
• git diff --check clean
• 12,128 additions / 53 deletions relative to main, including tests

Launch status

The code/config consolidation is ready for review. The new 42:1 row still requires the canonical ICE preflight plus a real optimizer-and-validation smoke before any full training launch.

Supersedes #4, #5, and #6 after review.