Replace raw string routerMessages with structured RouterEntry(role, content)
entries. User messages are stored locally on SubmitInput (both IDLE and
IN_SESSION). Router responses arrive as 'router' entries via
RouterResponseMessage. Tool diffs arrive as 'tool' entries.
RouterPanel renders as a styled conversation log with role prefixes:
▸ user msgs in accent, router replies in strong body, tool output in dim.
Multi-line content (diffs, long responses) is split on \n for proper display.
Panel title changed from 'router' to 'output' to reflect the log role.
kami
1f6680f774