[FR-005] Orchestrator runs automatic evaluator per task and stores JSON result

[explosivebit]

Trace: PRD prd-v0-1-smoke-evaluation-run · FR-005 · RFC implementation task 4

Capability: 3 evaluators (be_01_jwt_auth, fe_01_multistep_form, doc_01_cli_readme) produce evaluator_json per task-specific schema. be_01 uses Docker sandbox pinned by digest (architect finding #5 from EVID-005 SWE-bench).

Acceptance:

• Each evaluator deterministic on same input (NFR-003)
• Docker image for be_01 pinned by SHA digest, not tag
• Gold solution → evaluator → 100% pass