Adds Estonian to the settings language dropdown so accounts can select
the existing `et` translation from the UI.
Fixes: N/A
Closes: N/A
## Why
Estonian translation files already exist in the repo and in Crowdin, but
the settings dropdown is driven by `LANGUAGES_CONFIG`, where `et` was
missing.
## What this change does
- Adds `et` / `Eesti (et)` to `LANGUAGES_CONFIG`
- Makes Estonian available in the settings language selectors backed by
`enabledLanguages`
## Validation
- `ruby -c config/initializers/languages.rb`
- Opened the local UI at `/app/accounts/1/settings/general` and verified
`Eesti (et)` appears in the `Site language` dropdown
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Co-authored-by: Pranav <pranav@chatwoot.com>
44a7a13117