[feat] Add SP and PP kernels for qwen_moe true on policy

[maocheng23]

Stacked on top of #3.

Summary

Updates the SGLang contract metadata for the Qwen3-30B-A3B MoE SP+PP true-on-policy stack.

This PR is one of three coupled PRs that should be reviewed and landed together because they extend the qwen3_moe_true_on_policy_v1 contract to allow Megatron sequence parallel and pipeline parallel training while preserving SGLang rollout parity.

Companion PRs:

• Miles: [feat] Add SP and PP support for qwen_moe true on policy radixark/miles#1088
• Megatron-LM: [feat] Add SP and PP kernels for qwen_moe true on policy radixark/Megatron-LM#31

Main Changes

• Flip disable_megatron_sequence_parallel from True to False for the dense and MoE true-on-policy schemas.
• Keep SGLang runtime behavior unchanged; the deterministic TP/EP/MoE rollout policy is already provided by the MoE base PR, and this PR only updates the shared contract so Megatron SP is allowed.

Validation

Cleaned 8-GPU ion7 real-workload run:

• Run id: moe_sppp_pr_tp2_pp2_ep2_onpolicy_real3_cleaned_noci_nosave_260524_ion7
• Ray job: raysubmit_a9NCtiu6K5dRVCsc
• Topology: Megatron TP=2, PP=2, EP=2, ETP=1, sequence parallel enabled; SGLang 4 rollout engines, each TP=2, EP=2.
• Result: Ray job succeeded, all 8 GPUs returned to 0 MiB.
• Step 1: train/train_rollout_logprob_abs_diff=0.0, train/train_rollout_kl=0.0, grad_norm=0.0377418305, weight version 1.0, mixed version 0.0.
• Step 2: train/train_rollout_logprob_abs_diff=0.0, train/train_rollout_kl=0.0, grad_norm=0.0389085777, weight version 2.0, mixed version 0.0.
• Timing: cleaned step times 485.2571s and 462.8948s, about 2.6-2.9% slower than the previous on-policy no-debug timing run and in the same overhead band versus off-policy.

Focused checks after cleanup:

• git diff --check
• Miles fast checks: 53 passed
• Megatron targeted extension/MoE checks: 3 passed
• Megatron 8-rank tensor-parallel mapping check passed on all ranks
• Full SP+PP 8-GPU E2E exact-logprob rerun on ion7

Local record:
recovery/qwen3_moe_sppp_clean/journal/2026-05-23-sppp-e2e.md