All APIs from the http module are removed

Host meta data must be supplied by applications in the future so we can get rid of http requests

We have no use case for these attributes right now

This side effect was most likely a mistake, as:
- it is inconsistent with the other paths, e.g., when the pref_lang is available;
- a get_xxx() method having a side effect is generally not what one expects.

nicoco authored Sep 15, 2025 and Philipp Hörist committed Sep 16, 2025

From https://xmpp.org/extensions/xep-0045.html#subject-mod

> Note: A message with a <subject/> and a <body/> or a <subject/> and a <thread/> is a legitimate message, but it SHALL NOT be interpreted as a subject change.

Fixes #168

- Use datetime instead of float for timestamps
- Be more strict with parsing
- Reduce handlers used and simplify code