Problem

Currently we need to delete languages from LEK_languages to hide them in the frontend. This is dangerous and often causes problems with missing base-languages as we fetch base-languages for variants.

Solution

Add a column "hidden" to the LEK_languages table and add a filtered store "selectableLanguages" to the frontend which then is used by all selects, that select languages.
(Task-creation, LR-creation, Prompt-Management, Instant-Translate, Term-Portal, InstantTranslate & TermPortal may need other solutions, the List may be incomplete)
The issue includes adding a 2 CLI commands "LanguageDisable" and "LanguageEnable": t5 language:disable de-DE or t5 language:enable en-GB . Optionally, the language.id from the DB can be used as argument

Future extensions

Add a configuration frontend "Manage languages" to do the deactivation/activation via an UI in the preferences