Report when each kind of data was last updated #101

Problem

The manager can't tell whether the rates are fresh. If the events refresh or an upload failed yesterday, the rates may be stale and nothing says so.

Goal

One endpoint says when each kind of data was last successfully updated for a hotel.

Scope

• An endpoint, e.g. GET /hotels/{id}/freshness, returning the time of the last successful:
  • events refresh;
  • weather refresh;
  • hotel data upload;
  • training run;
  • recommendation snapshot.
• Also return whether the latest attempt of each kind failed, and when.
• Read from the existing jobs and snapshots; no new table.

Considerations

• Decide when each kind counts as stale (e.g. events older than a day) and return a flag, so the frontend doesn't have to know the rules.

Acceptance criteria

• The endpoint returns a time for each kind, or none if it has never run.
• A failed latest run is shown along with the last successful one.
• Tests cover never run, succeeded and failed.