* 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
