Fix Blender community E2E reproducibility

[senthilr-nv]

Description

Make the Blender Omniverse DGX Station example reproducible during a fresh community E2E deployment.

This fixes three failures found while following the published guide on a QA DGX Station:

• accept the current nvidia/nemotron-3-ultra-550b-a55b model ID in preflight instead of reporting a false failure;
• detach visible Blender from terminal stdin and run FFmpeg with -nostdin, preventing native OVPhysX replay from being job-control stopped;
• give Hermes one bounded run_configured_demo operation that runs preflight, prepare, preview, native simulation, and replay in order and returns a compact verified receipt.

The existing low-level helper operations remain available. The source .blend is preserved, each stage still verifies its host artifact, and the bounded workflow stops at the first failed stage.

Regression tests cover the successful workflow receipt and early termination after a blocked preflight.

Verification

• python scripts/check_license_headers.py --check — 186 source files passed on macOS and the QA DGX Station
• git diff --check
• Relevant example setup or syntax checks
  • bash -n examples/blender-omniverse-dgx-station/scripts/*.sh
  • Python compilation for all example scripts
  • python3 -m unittest discover -s examples/blender-omniverse-dgx-station/scripts -p 'test_*.py' — 11 tests passed on macOS and DGX
  • patched DGX preflight — 43 PASS, 6 expected WARN, 0 FAIL, RESULT=ready
  • fresh official-repository setup — model inference, 43 skills, raw and bounded MCP profiles, and Blender handoff passed
  • OVRTX render — 1920 x 1080 PNG produced with no fallback
  • unchanged stair-drop prompt — native OVPhysX pass-real, 12 bodies, 25 samples, verified 640 x 360 host GIF; source .blend checksum unchanged

Release And Compliance

• No secrets, local .env files, private certificates, snapshots, or token caches are included.
• Third-party dependency changes are reflected in THIRD-PARTY-NOTICES (no dependency changes).
• Public documentation is free of internal-only links or private workspace details.
• Commits include DCO sign-off (git commit -s).

Signed-off-by: Senthil Ravichandran senthilr@nvidia.com

[slopp]

lgtm