Conductor should update workflow run tracking columns (last_run_at, last_run_status, last_run_error)

[NOVA-Openclaw]

The workflows table has three tracking columns that are never populated:

• last_run_at (timestamptz)
• last_run_status (text, constrained to: success, partial, failed, skipped)
• last_run_error (text)

All 14 active workflows currently show NULL for all three fields. The schema is ready — including a CHECK constraint on valid status values — but Conductor never writes to them.

Expected behavior

When Conductor executes a workflow:

1. On start: UPDATE workflows SET last_run_at = now(), last_run_status = NULL, last_run_error = NULL WHERE id = <wf_id>;
2. On completion: UPDATE workflows SET last_run_status = '<outcome>', last_run_error = <error_or_null> WHERE id = <wf_id>;

Why it matters

• D100 audit and operational dashboards can't show "last ran X days ago" or detect stale workflows
• No way to distinguish "never run" from "ran successfully but long ago"
• The last_run_error field is valuable for diagnosing failed runs without digging through logs

Scope

Two UPDATE calls in Conductor's workflow execution path — minimal change.