* fix: use correct higlight color on selecting a tag in darkmode

* fix: take scrolling into account in tab suggestion

Issue: When editing a long memo and editing a tag somewhere where the user has
to scroll down to, the tag suggestions would be out of place (too far down)
because the scrolling wouldn't be taken into account.

Fix: Substract the suggestions div by the scroll amount.

* fix: don't show tag suggestion when on '#'

Fixes this issue like this:
1. Text #tag text
        ^ backspace here
2. Text#tag text
       ^ space
3. Text #tag text
        ^ tag suggestion opens

* fix: telegram callback query handler dereferencing nil pointer if memo not found

* chore: add an answer to callback query if memo not found

fix: Incorrectly checking whether registration is allowed in the login interface, resulting in the inability to log in through apiv1