Fix sequence creation timestamps to rely on recorded_at

[fe51]

Spotted reviewing frontend issue pyronear/new-pyro-platform#271, we have missed something in #617, mentionned #510

• Updates how detections are linked to sequences : Currently based on the created_at field, must be related to the recorded_at field

  • mainly in pyro-api/src/app/api/api_v1/endpoints/detections.py
  • updates creation rule and sequence creation/update of started_eat and last_seen_at fields

• check sequences fromdate endpoint to be sure it relies on started_at or if relies to created_at, updates to rely on recorded_at

In other words, the creation date of a sequence is always based on the “created at” time rather than the “recorded at” time

• Also, related migration needs to be performed

As a result, today we can correctly display a sequence’s detections using the “recorded at” time—for example, between 7:23 p.m. and 7:26 p.m.—but the sequence’s creation date (i.e., the alert start date) is shown as 7:25 p.m. This is confusing for users.

I’m available to discuss this, but at this stage, it’s preventing us from deploying “recorded_at” on the front end. @Acruve15 @MateoLostanlen ;)