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/en.ts

@@ -1401,8 +1401,6 @@ export const en = {
     output: "Output",
   },
   toolCallGroup: {
-    title: "Tools",
-    accessibilityLabel: "Tools, {{count}} calls",
     editedFiles: {
       one: "edited {{count}} file",
       other: "edited {{count}} files",
@@ -1527,13 +1525,12 @@ export const en = {
         description: "Show agent thinking and chain-of-thought blocks fully expanded by default",
       },
       toolCallDetail: {
-        label: "Tool call detail",
-        description: "How tool activity appears in agent timelines",
-        accessibilityLabel: "Select tool call detail ({{value}})",
+        label: "Tool call display",
+        description: "How tool calls appear in the timeline",
+        accessibilityLabel: "Select tool call display ({{value}})",
         options: {
-          overview: "Overview",
-          concise: "Concise",
-          detailed: "Detailed",
+          overview: "Summary",
+          detailed: "Full detail",
         },
       },
       language: {