fix: move History and Download buttons to Settings dialog for cleaner chat interface

lib/i18n/dictionaries/en.json

@@ -98,7 +98,11 @@
         "minimal": "Minimal",
         "sketch": "Sketch",
         "closeProtection": "Close Protection",
-        "closeProtectionDescription": "Show confirmation when leaving the page."
+        "closeProtectionDescription": "Show confirmation when leaving the page.",
+        "diagramActions": "Diagram Actions",
+        "diagramActionsDescription": "Manage diagram history and exports",
+        "history": "History",
+        "download": "Download"
     },
     "save": {
         "title": "Save Diagram",

lib/i18n/dictionaries/ja.json

@@ -98,7 +98,11 @@
         "minimal": "ミニマル",
         "sketch": "スケッチ",
         "closeProtection": "ページ離脱確認",
-        "closeProtectionDescription": "ページを離れる際に確認を表示します。"
+        "closeProtectionDescription": "ページを離れる際に確認を表示します。",
+        "diagramActions": "ダイアグラム操作",
+        "diagramActionsDescription": "ダイアグラムの履歴とエクスポートを管理",
+        "history": "履歴",
+        "download": "ダウンロード"
     },
     "save": {
         "title": "ダイアグラムを保存",

lib/i18n/dictionaries/zh.json

@@ -98,7 +98,11 @@
         "minimal": "简约",
         "sketch": "草图",
         "closeProtection": "关闭确认",
-        "closeProtectionDescription": "离开页面时显示确认。"
+        "closeProtectionDescription": "离开页面时显示确认。",
+        "diagramActions": "图表操作",
+        "diagramActionsDescription": "管理图表历史记录和导出",
+        "history": "历史记录",
+        "download": "下载"
     },
     "save": {
         "title": "保存图表",