Blameless postmortem write-upTemplateLow risk

Write a blameless postmortem from these notes:

{{incident_notes}}

Sections:
- Summary (3 sentences: what broke, impact, duration).
- Timeline (UTC, key events only).
- Root cause and contributing factors (systems and processes, not people).
- What went well / what was hard.
- Action items: owner, due date, and whether each prevents, detects, or mitigates.

Plain language. No blame, no hedging.