Add Japanese locale (ja) support (#1810)

* Add Japanese locale (ja) support

- New: ja.ts with 2624 UI translation keys
- New: ja.settings.ts with 1789 settings translation keys
- Registered ja in runtime.ts (Locale type, LOCALES, LOCALE_LABEL_KEYS, normalizeLocale)
- Added ja-JP BCP-47 mapping in intl.ts
- Added JA_MESSAGES in bootstrap.ts
- Added ja to lazy-load dictionary map in store.ts
- Updated messages.test.ts with ja dictionary
- Added common.language.japanese to all 8 existing locale files

* fix(i18n): complete Japanese locale updates

* test(i18n): enforce locale key parity

* docs: add Japanese documentation

---------

Co-authored-by: yuchi0531 <yuchi0531@users.noreply.github.com>
Co-authored-by: Bohdan Triapitsyn <artmore@protonmail.com>

packages/ui/src/lib/i18n/messages/fr.ts

@@ -13,6 +13,7 @@ export const dict = {
   'common.language.brazilianPortuguese': 'Portugais brésilien',
   'common.language.korean': 'Coréen',
   'common.language.polish': 'Polonais',
+  'common.language.japanese': 'Japonais',
   'common.revealPath.finder': 'Révéler dans le Finder',
   'common.revealPath.fileExplorer': 'Ouvrir dans l\'explorateur de fichiers',
   'common.revealPath.fileManager': 'Ouvrir dans le gestionnaire de fichiers',
@@ -103,6 +104,7 @@ export const dict = {
   'sessions.scheduledTasks.editor.scheduleType.daily': 'Tous les jours',
   'sessions.scheduledTasks.editor.scheduleType.weekly': 'Hebdomadaire',
   'sessions.scheduledTasks.editor.scheduleType.once': 'Une fois',
+  'sessions.scheduledTasks.editor.scheduleType.cron': 'Cron',
   'sessions.scheduledTasks.editor.date.label': 'Date',
   'sessions.scheduledTasks.editor.date.placeholder': 'Sélectionnez une date',
   'sessions.scheduledTasks.editor.date.previousMonth': 'Mois précédent',