feat(experimentalist): complete remote Harbor dependency runtime

[ryana]

Summary

• add bridge-owned Harbor dependency sessions for OpenShell execution
• route Rationalizer and TraceAnalyzer shell commands through the remote dependency runtime without exposing Docker to the sandbox
• validate dependency dataset/runtime conversion and propagate dependency failures explicitly
• pin OpenShell's NVIDIA provider to https://inference-api.nvidia.com/v1 and support platform-scoped profiles in OpenShell 0.0.92
• add a full-run OpenShell smoke harness and regression coverage

Validation

• uv run --frozen pytest plugins/nemo-experimentalist/tests -q -k 'not test_git_askpass_uses_provider_placeholders' — 595 passed, 1 deselected
• modified-file pre-commit hooks passed
• full local nemo experimentalist run smoke completed through Docker Desktop OpenShell and NVIDIA Inference Hub
• bridge evidence: 7 successful evaluations; dependency session 201 create, 10 stateful exec responses, and 204 close
• downloaded round analysis was non-empty and contained no analysis_error
• verified no OpenShell sandbox, bridge listener, or task container remained after cleanup

The deselected test uses Bash 4 ${prompt,,} syntax and is incompatible with macOS's system Bash 3.2; it is pre-existing and unrelated to this change.

One generated candidate omitted uv.lock and was rejected by the trusted bridge, so the smoke completed without a winner. The dependency-runtime path covered by this PR completed successfully.

Stack

• Base: feat(experimentalist): run in OpenShell with an external Harbor bridge #931
• Linear: AIRE-824