feat: Support plugin delegation tools in subagent UI view

[daixudk96-max]

Problem

Currently, the "View Sub Agents" UI feature only works for the built-in task tool. Plugin tools like delegate_task (from oh-my-opencode) correctly pass sessionId in metadata, but the UI doesn't recognize them because of a hardcoded tool name check in session-turn.tsx:

part.tool === "task" &&  // Only checks for "task"

Proposed Solution

Extend the condition to also recognize delegate_task:

(part.tool === "task" || part.tool === "delegate_task") &&

Benefits

• Enables plugins to leverage the same subagent UI experience
• No breaking changes to existing task tool behavior
• Better plugin ecosystem support

Context

This is needed for oh-my-opencode plugin which uses delegate_task for its multi-model agent orchestration feature.

[github-actions]

Thank you for the feature request! I've searched through existing issues and found that while there are related issues involving delegate_task, this appears to be a unique feature request focused on extending the subagent UI view to support plugin delegation tools.

Note: Issue #11342 also mentions delegate_task, but it's addressing a different bug (NotFoundError when using external servers) rather than UI support.

This feature request is specifically about enabling the "View Sub Agents" UI for plugin tools like delegate_task, which is not currently covered by existing issues.