fix(i18n): replace hardcoded Chinese strings in Session Manager

- Add i18n keys for relative time (justNow, minutesAgo, hoursAgo, daysAgo)
- Add i18n keys for role labels (roleUser, roleSystem, roleTool)
- Add i18n keys for UI elements (tocTitle, searchSessions, clickToCopyPath)
- Update formatRelativeTime and getRoleLabel to accept t function
- Add useTranslation hook to SessionToc component

src/i18n/locales/en.json

@@ -404,6 +404,7 @@
     "title": "Session Manager",
     "subtitle": "Manage Codex and Claude Code sessions",
     "searchPlaceholder": "Search by content, directory, or ID",
+    "searchSessions": "Search sessions",
     "providerFilterAll": "All",
     "sessionList": "Sessions",
     "loadingSessions": "Loading sessions...",
@@ -427,7 +428,16 @@
     "copySourcePath": "Copy source file",
     "sourcePathCopied": "Source file copied",
     "loadingMessages": "Loading transcript...",
-    "emptySession": "No messages available"
+    "emptySession": "No messages available",
+    "clickToCopyPath": "Click to copy path",
+    "tocTitle": "Contents",
+    "justNow": "Just now",
+    "minutesAgo": "{{count}} min ago",
+    "hoursAgo": "{{count}} hr ago",
+    "daysAgo": "{{count}} days ago",
+    "roleUser": "User",
+    "roleSystem": "System",
+    "roleTool": "Tool"
   },
   "console": {
     "providerSwitchReceived": "Received provider switch event:",

src/i18n/locales/ja.json

@@ -404,6 +404,7 @@
     "title": "セッション管理",
     "subtitle": "Codex / Claude Code のセッションを管理",
     "searchPlaceholder": "内容・ディレクトリ・ID で検索",
+    "searchSessions": "セッションを検索",
     "providerFilterAll": "すべて",
     "sessionList": "セッション一覧",
     "loadingSessions": "セッションを読み込み中...",
@@ -427,7 +428,16 @@
     "copySourcePath": "元ファイルをコピー",
     "sourcePathCopied": "元ファイルをコピーしました",
     "loadingMessages": "内容を読み込み中...",
-    "emptySession": "表示できる内容がありません"
+    "emptySession": "表示できる内容がありません",
+    "clickToCopyPath": "クリックしてパスをコピー",
+    "tocTitle": "目次",
+    "justNow": "たった今",
+    "minutesAgo": "{{count}}分前",
+    "hoursAgo": "{{count}}時間前",
+    "daysAgo": "{{count}}日前",
+    "roleUser": "ユーザー",
+    "roleSystem": "システム",
+    "roleTool": "ツール"
   },
   "console": {
     "providerSwitchReceived": "プロバイダー切り替えイベントを受信:",

src/i18n/locales/zh.json

@@ -404,6 +404,7 @@
     "title": "会话管理",
     "subtitle": "管理 Codex 与 Claude Code 会话记录",
     "searchPlaceholder": "搜索会话内容、目录或 ID",
+    "searchSessions": "搜索会话",
     "providerFilterAll": "全部",
     "sessionList": "会话列表",
     "loadingSessions": "加载会话中...",
@@ -427,7 +428,16 @@
     "copySourcePath": "复制原始文件",
     "sourcePathCopied": "原始文件已复制",
     "loadingMessages": "加载会话内容中...",
-    "emptySession": "该会话暂无可展示内容"
+    "emptySession": "该会话暂无可展示内容",
+    "clickToCopyPath": "点击复制路径",
+    "tocTitle": "对话目录",
+    "justNow": "刚刚",
+    "minutesAgo": "{{count}} 分钟前",
+    "hoursAgo": "{{count}} 小时前",
+    "daysAgo": "{{count}} 天前",
+    "roleUser": "用户",
+    "roleSystem": "系统",
+    "roleTool": "工具"
   },
   "console": {
     "providerSwitchReceived": "收到供应商切换事件:",