stage-367: locale-parity fix for settings_tab_plugins (10 locales)

PR #2367 added settings_tab_plugins to English only. The locale-parity
tests (test_chinese_locale.py, test_japanese_locale.py, etc.) require
every English key to exist in all 10 other locales. CI failed on 5 of them.

Adds the key to all 10 non-English locales with translations:
- it: Plugin, ja: プラグイン, ru: Плагины, es/de/pt/fr: Plugins (loanword),
  zh: 插件, zh-TW: 外掛, ko: 플러그인

Co-authored-by: mccxj <mccxj@users.noreply.github.com>

static/i18n.js

@@ -1698,6 +1698,7 @@ const LOCALES = {
     settings_tab_conversation: 'Conversazione',
     settings_tab_appearance: 'Aspetto',
     settings_tab_preferences: 'Preferenze',
+    settings_tab_plugins: 'Plugin',
     settings_tab_system: 'Sistema',
     settings_title: 'Impostazioni',
     settings_save_btn: 'Salva Impostazioni',
@@ -2879,6 +2880,7 @@ const LOCALES = {
     settings_tab_conversation: '会話',
     settings_tab_appearance: '外観',
     settings_tab_preferences: '環境設定',
+    settings_tab_plugins: 'プラグイン',
     settings_tab_system: 'システム',
     settings_title: '設定',
     settings_save_btn: '設定を保存',
@@ -4565,6 +4567,7 @@ const LOCALES = {
     settings_tab_appearance: 'Appearance',
     settings_tab_conversation: 'Conversation',
     settings_tab_preferences: 'Preferences',
+    settings_tab_plugins: 'Плагины',
     settings_tab_system: 'System',
     status_updated: 'Updated',
     status_ephemeral: 'Ephemeral snapshot — not saved to transcript history.',
@@ -5673,6 +5676,7 @@ const LOCALES = {
     settings_tab_appearance: 'Appearance',
     settings_tab_conversation: 'Conversation',
     settings_tab_preferences: 'Preferences',
+    settings_tab_plugins: 'Plugins',
     settings_tab_system: 'System',
     status_updated: 'Updated',
     status_ephemeral: 'Ephemeral snapshot — not saved to transcript history.',
@@ -6517,6 +6521,7 @@ const LOCALES = {
     settings_tab_appearance: 'Appearance',
     settings_tab_conversation: 'Conversation',
     settings_tab_preferences: 'Preferences',
+    settings_tab_plugins: 'Plugins',
     settings_tab_system: 'System',
     status_updated: 'Updated',
     status_ephemeral: 'Ephemeral snapshot — not saved to transcript history.',
@@ -7910,6 +7915,7 @@ const LOCALES = {
     settings_tab_appearance: '外观',
     settings_tab_conversation: '对话',
     settings_tab_preferences: '偏好',
+    settings_tab_plugins: '插件',
     settings_tab_system: '系统',
     status_updated: '已更新',
     status_ephemeral: '临时快照 — 不会保存到对话记录。',
@@ -8369,6 +8375,7 @@ const LOCALES = {
     settings_tab_conversation: '對話',
     settings_tab_appearance: '外觀',
     settings_tab_preferences: '偏好設定',
+    settings_tab_plugins: '外掛',
     settings_tab_system: '系統',
     settings_title: '\u8a2d\u5b9a',
     settings_save_btn: '\u5132\u5b58\u8a2d\u5b9a',
@@ -9638,6 +9645,7 @@ const LOCALES = {
     settings_tab_conversation: 'Conversa',
     settings_tab_appearance: 'Aparência',
     settings_tab_preferences: 'Preferências',
+    settings_tab_plugins: 'Plugins',
     settings_tab_system: 'Sistema',
     settings_title: 'Configurações',
     settings_save_btn: 'Salvar Configurações',
@@ -10722,6 +10730,7 @@ const LOCALES = {
     settings_tab_conversation: '대화',
     settings_tab_appearance: '외형',
     settings_tab_preferences: '환경설정',
+    settings_tab_plugins: '플러그인',
     settings_tab_system: '시스템',
     settings_title: '설정',
     settings_save_btn: '설정 저장',
@@ -11823,6 +11832,7 @@ const LOCALES = {
     settings_tab_conversation: 'Conversation',
     settings_tab_appearance: 'Apparence',
     settings_tab_preferences: 'Préférences',
+    settings_tab_plugins: 'Plugins',
     settings_tab_system: 'Système',
     settings_title: 'Paramètres',
     settings_save_btn: 'Enregistrer les paramètres',