Wire core sidebar tabs to PhoenixKitWeb.Gettext for ru/et

[timujinne]

Summary

Phase 3 of per-module i18n migration (Q7, deferred from PR #522). Core admin sidebar tabs now carry gettext_backend: PhoenixKitWeb.Gettext so Tab.localized_label/1 translates them at render time — matching the behaviour already working for external module tabs (Newsletters, Billing, Emails, etc.).

Changes

lib/phoenix_kit/dashboard/admin_tabs.ex

• Added gettext_backend: PhoenixKitWeb.Gettext to 6 explicit %Tab{} literals: :admin_dashboard, :admin_users, :admin_activity, :admin_media, :admin_settings, :admin_settings_media
• Orchestrator prior work preserved: admin_subtab/8 helper (covers 13 subtabs) + :admin_modules_page

lib/phoenix_kit/dashboard/registry.ex

• Added gettext_backend: PhoenixKitWeb.Gettext to user-dashboard defaults: :dashboard_home, :dashboard_settings

lib/phoenix_kit/jobs.ex

• Added gettext_backend: PhoenixKitWeb.Gettext to :admin_jobs Tab

priv/gettext/ru/LC_MESSAGES/default.po

• Filled 5 existing empty msgstr: Permissions, Settings, Health, Integrations, Organization
• Appended 13 new entries: Manage Users, Live Sessions, Referral Codes, Activity, Media, General, Authorization, Dimensions, Jobs, Languages, SEO, Sitemap, Home

priv/gettext/et/LC_MESSAGES/default.po

• Filled existing empty msgstr for Dashboard, Users, Roles, Sessions, Permissions, Settings, Health, Integrations, Organization
• Appended 14 new entries (same 13 as ru + Modules)

Verification

Verified live on decor_3d_print (port 4001) after mix deps.compile phoenix_kit --force. Sample output under ru locale:

admin_dashboard → Панель управления
admin_users → Пользователи
admin_users_manage → Управление пользователями
admin_users_live_sessions → Активные сессии
admin_users_sessions → Сессии
admin_users_roles → Роли
admin_activity → Активность
admin_users_permissions → Разрешения
admin_media → Медиа
admin_jobs → Задачи
admin_modules_page → Модули
admin_settings → Настройки
admin_settings_general → Общие
admin_settings_authorization → Авторизация
admin_settings_organization → Организация
admin_settings_integrations → Интеграции
admin_settings_media → Медиа
dashboard_home → Панель управления
dashboard_settings → Настройки

Out of scope (separate follow-up sweeps)

• Body strings on admin LiveView pages (sweep B)
• Other locales (de/es/fr/it/pl) — fall back to English msgid
• Module-side packages (done in Phase 2)

[timujinne]

Additional commit c717c9d0 cherry-picked into this branch: Wrap MediaBrowser UI strings in gettext + add ru/et translations.

Scope (out of the original PR description):

• lib/phoenix_kit_web/components/media_browser.{ex,html.heex} — all user-facing strings (buttons, titles, tooltips, placeholders, empty states, flash notifications, confirm dialogs) routed through gettext / ngettext.
• lib/phoenix_kit_web/live/users/media.{ex,html.heex} — page title + admin header strings.
• priv/gettext/default.pot + locale .po files — extract & merge.
• Russian (3-form plurals) and Estonian (2-form plurals) translations filled in priv/gettext/{ru,et}/LC_MESSAGES/default.po. Other locales fall back to the English msgid.

[timujinne]

Post-merge review of the MediaBrowser i18n cherry-pick (c717c9d0)

For the record, here is a follow-up review of the MediaBrowser i18n changes in this PR. The sidebar-tabs piece (the original PR scope) reviewed clean. Findings below apply only to the cherry-picked commit and can be addressed in a follow-up PR if/when needed.

Major

1. Three strings in list-view duplicate of the folder dropdown were not wrapped, while their grid-view twins were. Users will see mixed languages when switching to list view.

   • lib/phoenix_kit_web/components/media_browser.html.heex:1047 — Color heading
   • lib/phoenix_kit_web/components/media_browser.html.heex:1078 — data-confirm={"Delete '#{folder.name}'? Files move to parent."} (raw interpolation)
   • lib/phoenix_kit_web/components/media_browser.html.heex:1081 — Delete button text

   Grid-view counterparts at :735, :766, :769 are correctly wrapped.

2. Three messages embed two independent counts in a single gettext call, making correct pluralization impossible in Russian (3 forms) and Estonian (2 forms). The translator was forced to write awkward файл(ов) / папк(у/и) constructions.

   • lib/phoenix_kit_web/components/media_browser.ex:1743 — build_partial_success_message: %{new} file(s) uploaded, %{err} failed
   • lib/phoenix_kit_web/components/media_browser.ex:1770 — build_new_and_duplicates_message: %{new} new file(s) added. %{dup} file(s) were already uploaded
   • lib/phoenix_kit_web/components/media_browser.ex:1879 — delete_selected_confirm, files+folders branch: Delete %{files} file(s) and %{folders} folder(s)?

   Fix pattern — compose two ngettext results and inject via gettext:

   files_str = ngettext("%{count} file", "%{count} files", new_count)
   errors_str = ngettext("%{count} failed", "%{count} failed", error_count)
   gettext("Partially successful: %{files} uploaded, %{errors} due to missing storage buckets.",
     files: files_str, errors: errors_str)

Minor

• %{count} selected (ru): current msgstr[0] = "%{count} выбран" implies masculine gender, which is wrong for folders (feminine). Prefer a neutral predicative: «Выбрано: %{count}» across all three forms.
• String.upcase(f.file_type || "FILE") at media_browser.html.heex:1339, 1367 — fallback "FILE" is shown to the user but not localized. Arguable since it acts as a technical label.

Cherry-pick history note

Duplicate commit titles in history (d44bf95c on dev, c717c9d0 in this branch — same content). Resolved naturally by the merge.