Allow editing subagent conversation names in UI

[exedev-shelley]

Author: realami
Channel: #feedback
Link: https://discord.com/channels/1405685085923049482/1405686161791516873/1471673484429234311

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Description

Add the ability to edit the names of subagent conversations directly through the UI.

Current Workaround

Currently, the only way to rename a subagent conversation is to:

1. Use sqlite3 directly on the parent conversation database
2. Have the parent conversation agent rename it

Note: The agent within a subconversation claims to be unable to rename its own conversation, even though this is technically possible.

Desired Behavior

Users should be able to edit subagent conversation names directly in the UI, similar to how they can rename other conversations.