Fix perf loading ModelKit build output directories

[fangyangci]

Summary

• Resolve marked ModelKit build output directories to their final model.onnx before perf CLI and programmatic dispatch.
• Preserve local HF directory handling and report incomplete build outputs clearly.
• Document the supported layout and add CLI/programmatic regression coverage for both build markers.

Fixes #1449.

Validation

• 274 related unit tests passed (perf CLI, perf GenAI, model input).
• Ruff lint and format checks passed.