[FEATURE]: Show relationship between parent session and subagents, with navigation

[jmagder]

Feature hasn't been suggested before.

• I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

I feel in love with opencode seeing it flawlessly run multiple subagents in a context efficient way. I was however, frustrated I couldn't see those subagents in the web UX. So I built the feature!

PR at: #14043 which has a video demo. :D

[github-actions]

This issue might be related to existing feature requests exploring similar functionality:

• [FEATURE]: Navigation to parent session from child/subagent sessions #3291: Navigation to parent session from child/subagent sessions (keybinding approach)
• [FEATURE]: improved visual position indicator for subagent sessions #9989: Improved visual position indicator for subagent sessions
• feat: Add /subagents command to view subagent tree #6299: Add /subagents command to view subagent tree (TUI approach)

Your implementation appears to add visual relationship display in the web UX, which complements these other requests. You may want to review them to ensure alignment or identify areas for cross-feature coordination.