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
d502f604fcJulius Marminge committed on 9/5/2026, 4:54:18 AMparent3edc22d
15 files changedLine totals unavailable