Phase 80: refresh source graph after source saves

[pcharbon70]

Summary

• add the Phase 80 plan for save-triggered source graph refresh adoption
• add repo-scoped source-change observation for local watcher events and product-managed write notifications
• add debounced per-repo source graph refresh scheduling through AgentWorkspace lifecycle entrypoints
• expose refresh queue/running/failure state in source graph status projections and semantic hints
• document refresh configuration and add Phase 80 integration coverage for human and LLM save paths

Verification

• mix test test/jido_code/phase_eighty_integration_test.exs test/jido_code/repo_monitor_source_watcher_test.exs test/jido_code/source_code_graph_refresh_scheduler_test.exs test/jido_code/source_code_graph_product_service_test.exs test/jido_code/source_code_graph_workspace_test.exs
• mix source_graph.verify

Note: bw prime and bw ready were attempted before work, but bw is not installed in this environment.