Hide subagent threads and simplify thread controls

- Remove subagent prefixes from titles and timeline labels
- Hide subagent threads in the sidebar and add parent-thread navigation
- Align thread details, picker, and git/script controls with panel styling
a5e924aa75Julius Marminge committed on 8/29/2026, 6:01:03 AMparent12bf290
15 files changedLine totals unavailable