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
56ce5f9b42Julius Marminge committed on 9/1/2026, 4:24:39 AMparent7d24a0c
15 files changedLine totals unavailable