[VideoGenX] run matched H3 workloads on SGLang and vLLM-Omni

[edwingao28]

Description

Run H3 on both engines through native sweeps, with one hashed 20-clip workload, pinned runtimes, and sealed execution evidence.

Validation	Result
Producer → App	Both synthetic engine bundles passed archive-to-History regression.
CI	Tests/lint/spec/Zizmor passed at 07638040.
Matrix	Exactly two H200 rows; affected-key validation uses #4274 tooling.
H100/a8576ccb	One vLLM-Omni clip, submission through validation: 125.4 s; informational only.

Blocker: Depends on #2916. Matched H200 GPU qualification remains unverified.

PR checklist and change type

Type of Change

• Bug fix
• New feature
• Configuration change
• Documentation update
• Other (please describe)

Checklist

• I have tested my changes locally
• I have updated documentation if necessary
• If python -m infx.matrix.changed --base origin/main lists affected config keys, I have appended one new entry covering them to the physical end of inferencex-e2e/perf-changelog.yaml; if it lists none, I have added none. I have not edited historical entries
• If this PR appends an inferencex-e2e/perf-changelog.yaml entry, it carries exactly one primary sweep label (a maintainer applies it on fork PRs): full-sweep-fail-fast (recommended), full-sweep-enabled, or non-canary-full-sweep-enabled. Optional modifiers all-evals, evals-only, and agentx-fast require a primary label; the last two block reuse while applied.
• Before merging via reuse, an authorized maintainer (OWNER/MEMBER/COLLABORATOR) has commented /use <run_id> (or the legacy /reuse-sweep-run) on this PR. Do this only once there is a final full sweep that is all green with evals passing, since after this comment the primary sweep label will no longer automatically kick off new sweeps. Remove and re-add the primary sweep label to force a new sweep.