Mentat

Currently if user does not provide ending timestamp, the field stays "open", and submitting the query again might result in different results (new incoming data). That's bad for repeatability and determinism - and consequently caching, for instance.

Let's make timestamp fixed at the time of query submission, so query form of result page will not bring empty ending timestamp, but the fixed one. If the user needs to get new data, he can rewrite or empty the ending timestamp contents again.