Fix Redis session DSN, remove LibreTranslate from prod, track all translations

- Fix SESSION_HANDLER_DSN: use Redis db index (/1) instead of /sessions
  which caused "dbindex must be a number" error
- Remove LibreTranslate service and volume from docker-compose prod
- Remove gitignore rules for translation files (en, es, de, it)
  so all languages are tracked in git
- Apply PHP CS Fixer style fixes

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitignore

@@ -27,13 +27,6 @@ node_modules/
 /coverage/
 /coverage-clover.xml
 
-###> translations (auto-generated, only FR is source) ###
-/translations/*.en.yaml
-/translations/*.es.yaml
-/translations/*.de.yaml
-/translations/*.it.yaml
-###< translations ###
-
 ###> friendsofphp/php-cs-fixer ###
 /.php-cs-fixer.php
 /.php-cs-fixer.cache