Fix terminal finalize convergence and dashboard fanout

[yvette-carlisle]

Summary

• Project terminal-finalize private events into operator status/lane inspect as terminal lifecycle writeback instead of active or stalled execution.
• Disable hard-interrupt fallback for phase = terminal_pending rows and keep terminal writeback out of active-lane control paths.
• Bound dashboard websocket fanout, unregister closed clients, and serve cached runActivity on connect/control refresh so browser reconnect storms cannot synchronously rebuild full run activity per socket and starve intake.
• Sync Decodex skills/reference docs with the new terminal_pending operator semantics.

Issues

• Fixes XY-917
• Fixes XY-919

Validation

• cargo make fmt
• git diff --check
• cargo test -p decodex dashboard_event_hub --all-features -- --test-threads=1
• cargo test -p decodex operator_state_endpoint --all-features -- --test-threads=1
• cargo test -p decodex operator_dashboard --all-features -- --test-threads=1
• cargo test -p decodex operator_status_projects_terminal_finalized_run_as_pending_not_active --all-features -- --test-threads=1
• cargo test -p decodex operator_status_snapshot --all-features -- --test-threads=1
• cargo test -p decodex operator_lane --all-features -- --test-threads=1
• cargo test -p decodex plugin_surface --all-features -- --test-threads=1
• cargo make check-rust
• cargo make test (1046 passed, 1 skipped)