Manage incidents from the admin area, like maintenance

📑 I have found these related issues/pull requests #862 — Incident Timeline (closed, implemented via #6469). This builds on that work rather than duplicating it. #6932 — Adding an incident tracker like Betterstack (closed as completed). #7523 — Add Incident automatically if some monitor is down (closed as duplicate). This request is explicitly *not* that: incidents stay created and resolved by a human. Only where they are managed from would change. #7080 — Degrade status page if there is an active Incident (open, adjacent). 🔖 Feature description Incidents can currently only be managed from inside a status page: open the page, click "Edit", create or edit the incident, then save the whole page, then leave edit mode to see the result. Maintenance, by contrast, is a first-class section in the admin area, with its own list, its own form, and selectors for the monitors and status pages it applies to. Incidents and maintenance serve the same purpose — telling users what is hap…