Complete search functionality with multi-language support and testing

Co-authored-by: PeterDaveHello <3691490+PeterDaveHello@users.noreply.github.com>

Author: Copilot

src/_locales/es/main.json

@@ -97,6 +97,8 @@
   "Delete Conversation": "Eliminar conversación",
   "Clear conversations": "Borrar todas las conversaciones",
   "Settings": "Configuración",
+  "Search": "Buscar",
+  "Search conversations...": "Buscar conversaciones...",
   "Feature Pages": "Páginas de características",
   "Keyboard Shortcuts": "Atajos de teclado",
   "Open Conversation Page": "Abrir página de conversación independiente",

src/_locales/fr/main.json

@@ -97,6 +97,8 @@
   "Delete Conversation": "Supprimer la conversation",
   "Clear conversations": "Effacer les conversations",
   "Settings": "Paramètres",
+  "Search": "Rechercher",
+  "Search conversations...": "Rechercher des conversations...",
   "Feature Pages": "Pages de fonctionnalités",
   "Keyboard Shortcuts": "Raccourcis clavier",
   "Open Conversation Page": "Ouvrir la page de conversation",

src/_locales/ja/main.json

@@ -97,6 +97,8 @@
   "Delete Conversation": "会話を削除",
   "Clear conversations": "会話をクリア",
   "Settings": "設定",
+  "Search": "検索",
+  "Search conversations...": "会話を検索...",
   "Feature Pages": "機能ページ",
   "Keyboard Shortcuts": "キーボードショートカット",
   "Open Conversation Page": "会話ページを開く",

src/_locales/zh-hant/main.json

@@ -97,6 +97,8 @@
   "Delete Conversation": "刪除對話",
   "Clear conversations": "清空對話記錄",
   "Settings": "設定",
+  "Search": "搜尋",
+  "Search conversations...": "搜尋聊天記錄...",
   "Feature Pages": "功能頁面",
   "Keyboard Shortcuts": "快速鍵設定",
   "Open Conversation Page": "開啟獨立對話頁面",