ci: add simulator pull request tests

[dddddddxl]

Summary

• add a PR and manual GitHub Actions workflow on the nmz3 BW1100 runner
• test the checked-out PR merge revision with the fixed hcu-train-simulator:1.0.0 image
• run Dense, MoE, and MLA/MTP simulation ST cases
• keep the test container offline, read-only, and resource constrained
• stream source into an in-memory container workspace for nmz3 Docker policy compatibility

Validation

• nmz3 local container validation: 3/3 tests passed
• GitHub Actions is queued for the currently occupied ci-nmz3 runner