feat: create maintenance incident type via API

[borisjacquot]

Hi! I wanted to create a Maintenance via the API but it is currently not possible.

Summary

This PR allows to give 2 more parameters in the API:

• incident_type
• end_date_time

It also adds a new check inside CreateIncident() in order to avoid dirty values in the DB.

API calls

Create a Maintenance

POST /api/incident
{
    "title": "Test maintenance",
    "start_date_time": 1762268631,
    "end_date_time": 1762272231,
    "incident_type": "MAINTENANCE"
}

RESPONSE -> 201
{
    "id": 9,
    "start_date_time": 1762268631,
    "end_date_time": 1762272231,
    "created_at": "2025-11-04 12:42:52",
    "updated_at": "2025-11-04 12:42:52",
    "title": "Test maintenance",
    "status": "OPEN",
    "state": "INVESTIGATING"
}

Create an incident with a wrong type

POST /api/incident
{
    "title": "Test maintenance",
    "start_date_time": 1762260039,
    "end_date_time": 1762268631,
    "incident_type": "MAINTENANCEEEE"
}

RESPONSE -> 400
{
    "error": "Incident type must be either INCIDENT or MAINTENANCE"
}

Notes

I noticed that creating a maintenance in this way, the state was set to "INVESTIGATING" instead of "RESOLVED" (when creating via web UI). It looks impactless but I'm not aware of the whole workflows.

Fixes #468