Refine tool call summaries and scrolling (#2069)

* feat(app): refine tool call summaries and scrolling

Keep summary groups stable from the first tool call, preserve live activity feedback, and scroll expanded groups to the latest entry. Consolidate web scrollbar styling around the native browser mechanism.

* refactor(app): reuse tool call height constant

* fix(app): preserve tool call summary state

* fix(app): refresh web tool groups on expand

* fix(app): preserve grouped tool errors

packages/app/src/i18n/resources/ja.ts

@@ -1410,8 +1410,6 @@ export const ja: TranslationResources = {
     output: "出力",
   },
   toolCallGroup: {
-    title: "ツール",
-    accessibilityLabel: "ツール、{{count}}件の呼び出し",
     editedFiles: {
       one: "{{count}}個のファイルを編集",
       other: "{{count}}個のファイルを編集",
@@ -1536,13 +1534,12 @@ export const ja: TranslationResources = {
         description: "デフォルトでAIのエージェント思考・推論ブロックを完全に展開して表示します",
       },
       toolCallDetail: {
-        label: "ツール呼び出しの詳細",
-        description: "エージェントのタイムラインでのツール活動の表示方法",
-        accessibilityLabel: "ツール詳細を選択（{{value}}）",
+        label: "ツール呼び出しの表示",
+        description: "タイムラインでのツール呼び出しの表示方法",
+        accessibilityLabel: "ツール呼び出しの表示を選択（{{value}}）",
         options: {
-          overview: "概要",
-          concise: "簡潔",
-          detailed: "詳細",
+          overview: "要約",
+          detailed: "すべての詳細",
         },
       },
       language: {