Implemented the Cortex-side network graph job.

Key changes:

  • Added stakeholder_graph_view input validation in handoff_contract.py.
  • Wired graph snapshot generation in stakeholder_signal_store.py. It now builds scoped subgraphs, scores nodes/edges, emits warm-intro and shared-alumni paths, writes JSON under the external DB root graph_views/, and includes filter metadata.
  • Added the queue handler in stakeholder_graph_view.py and registered it in init.py.
  • Updated the local worker supported types in worker/config.env so the running worker can claim stakeholder_graph_view.
  • Added coverage in test_handoff_contract_validation.py and test_stakeholder_signal_store.py, including an end-to-end graph-view payload test.

Verification passed:

  • pytest -q tests/unit/test_handoff_contract_validation.py tests/unit/test_stakeholder_signal_store.py
  • python -m compileall cortex_engine/handoff_contract.py cortex_engine/stakeholder_signal_store.py worker/handlers/ stakeholder_graph_view.py worker/handlers/init.py