fix: comprehensive i18n — replace hardcoded French/English strings with t() calls

Replaced ~100+ hardcoded French and English text strings across 30+ components
with proper i18n t() calls. Added 57 new translation keys to all 15 locale files
(ar, de, en, es, fa, fr, hi, it, ja, ko, nl, pl, pt, ru, zh).

Key changes:
- contextual-ai-chat.tsx: 30 French strings → t() (actions, toasts, labels, placeholders)
- ai-chat.tsx: 15 French/English strings → t() (header, tabs, welcome, insights, history)
- note-inline-editor.tsx: 20 French fallbacks removed (toolbar, save status, checklist)
- lab-skeleton.tsx: French loading text → t()
- admin-header.tsx, header.tsx, editor-connections-section.tsx: French fallbacks removed
- New AI chat component, agent cards, sidebar, settings panel i18n cleanup

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

memento-note/locales/zh.json

@@ -81,7 +81,30 @@
       "noModels": "无模型。点击 ↺",
       "modelsAvailable": "{count} 个模型可用",
       "enterUrlToLoad": "输入URL并点击↺加载模型",
-      "currentProvider": "(当前: {provider})"
+      "currentProvider": "(当前: {provider})",
+      "pageTitle": "AI管理",
+      "pageDescription": "监控和配置AI功能",
+      "configure": "配置",
+      "features": "AI功能",
+      "providerStatus": "AI提供商状态",
+      "recentRequests": "最近的AI请求",
+      "comingSoon": "即将推出",
+      "activeFeatures": "活跃功能",
+      "successRate": "成功率",
+      "avgResponseTime": "平均响应时间",
+      "configuredProviders": "已配置提供商",
+      "settingUpdated": "设置已更新",
+      "updateFailedShort": "更新失败",
+      "titleSuggestions": "标题建议",
+      "titleSuggestionsDesc": "在50+字后为笔记建议标题",
+      "aiAssistant": "AI助手",
+      "aiAssistantDesc": "启用AI聊天和文本改进工具",
+      "memoryEchoFeature": "我注意到了...",
+      "memoryEchoFeatureDesc": "每日分析笔记之间的联系",
+      "languageDetection": "语言检测",
+      "languageDetectionDesc": "自动检测每条笔记的语言",
+      "autoLabeling": "自动标记",
+      "autoLabelingDesc": "自动建议并应用标签"
     },
     "aiTest": {
       "description": "测试您的 AI 提供商的标签生成和语义搜索嵌入",
@@ -195,7 +218,9 @@
         "email": "邮箱",
         "name": "姓名",
         "role": "角色"
-      }
+      },
+      "title": "用户",
+      "description": "管理用户和权限"
     },
     "chat": "AI 聊天",
     "lab": "实验室",
@@ -231,7 +256,18 @@
       "testing": "测试中...",
       "testSearch": "测试网络搜索"
     },
-    "settingsDescription": "配置应用程序设置"
+    "settingsDescription": "配置应用程序设置",
+    "dashboard": {
+      "title": "仪表板",
+      "description": "应用程序指标概览",
+      "recentActivity": "最近活动",
+      "recentActivityPlaceholder": "最近的活动将在此处显示。"
+    },
+    "error": {
+      "title": "管理面板出错",
+      "description": "页面渲染失败。您可以重试。",
+      "retry": "重试"
+    }
   },
   "ai": {
     "analyzing": "AI 分析中...",
@@ -322,7 +358,57 @@
     "translationFailed": "翻译失败",
     "undo": "撤销 AI",
     "undoAI": "撤销 AI 转换",
-    "undoApplied": "已恢复原始文本"
+    "undoApplied": "已恢复原始文本",
+    "minWordsError": "笔记必须至少包含5个字才能使用AI操作。",
+    "genericError": "AI错误",
+    "actionError": "AI操作期间出错",
+    "appliedToNote": "已应用到笔记",
+    "applyToNote": "应用到笔记",
+    "undoLastAction": "撤销上次AI操作",
+    "selectContext": "选择上下文...",
+    "selectNotebook": "选择笔记本",
+    "chatPlaceholder": "让AI编辑、总结或起草...",
+    "assistantTitle": "AI助手",
+    "currentNote": "当前笔记",
+    "shrinkPanel": "收缩面板",
+    "expandPanel": "展开面板",
+    "chatTab": "聊天",
+    "noteActions": "笔记操作",
+    "askToStart": "向助手提问以开始。",
+    "contextLabel": "上下文",
+    "thisNote": "此笔记",
+    "allMyNotes": "所有笔记",
+    "notebookGeneric": "笔记本",
+    "writingTone": "写作语气",
+    "askAboutThisNote": "向AI提问关于此笔记...",
+    "askAboutYourNotes": "向AI提问关于你的笔记...",
+    "webSearchLabel": "网页搜索",
+    "newLineHint": "Shift+Enter = 换行",
+    "resultLabel": "结果",
+    "discardAction": "丢弃",
+    "transformationsDesc": "转换 — 直接应用到笔记",
+    "writeMinWordsAction": "至少写5个字以激活AI操作。",
+    "processingAction": "处理中...",
+    "action": {
+      "clarify": "澄清",
+      "shorten": "缩短",
+      "improve": "改进",
+      "toMarkdown": "转为Markdown"
+    },
+    "openAssistant": "打开AI助手",
+    "poweredByMomento": "由 Momento AI 提供支持",
+    "welcomeMsg": "你好！我是你的AI助手。今天我能怎么帮你的笔记？我可以优化语气、扩展内容或总结。",
+    "summaryLast5": "最近5条笔记摘要",
+    "analyzingProgress": "分析中...",
+    "generateInsightsBtn": "生成洞察",
+    "newDiscussion": "新对话",
+    "noRecentConversations": "没有最近的对话。",
+    "discussionContextLabel": "讨论上下文",
+    "webSearchNotConfigured": "网页搜索（未配置）",
+    "historyTab": "历史",
+    "insightsTab": "洞察",
+    "aiCopilot": "AI副驾驶",
+    "suggestTitle": "AI标题建议"
   },
   "aiSettings": {
     "description": "配置您的 AI 驱动功能和偏好设置",
@@ -907,7 +993,12 @@
     "viewModeGroup": "笔记显示模式",
     "reorderTabs": "重新排序标签页",
     "modified": "已修改",
-    "created": "已创建"
+    "created": "已创建",
+    "loading": "加载中...",
+    "exportPDF": "导出PDF",
+    "savedStatus": "已保存",
+    "dirtyStatus": "已修改",
+    "completedLabel": "已完成"
   },
   "pagination": {
     "next": "→",
@@ -999,7 +1090,8 @@
     "searchPlaceholder": "搜索您的笔记...",
     "searching": "搜索中...",
     "semanticInProgress": "AI 搜索进行中...",
-    "semanticTooltip": "AI 语义搜索"
+    "semanticTooltip": "AI 语义搜索",
+    "disabledAdmin": "管理员模式下搜索已禁用"
   },
   "semanticSearch": {
     "exactMatch": "完全匹配",
@@ -1440,5 +1532,9 @@
     "markUndone": "标记为未完成",
     "todayAt": "今天 {time}",
     "tomorrowAt": "明天 {time}"
+  },
+  "lab": {
+    "initializing": "初始化工作区",
+    "loadingIdeas": "加载你的想法..."
   }
 }