agents view drops the original session from the list after /branch

When forking a session with /branch from inside the claude agents dashboard, the original (pre-branch) session disappears from the agents table view. The new branched session appears (correctly tagged with forkedFrom), but the parent session is no longer listed under Pinned/Needs input/Completed.

This appears to be purely a UI listing gap, not data loss — the original session's .jsonl file remains fully intact on disk and is still reachable via claude --resume / the /resume picker.

Repro:

1. Create a new session (e.g. name it "New session test")
2. Run /branch <name> (e.g. "Session Test 2")
3. Detach back to the agents table view
4. Only "Session Test 2" appears — the original session is missing from the table

Expected: both the original and the forked session should appear as separate rows in the agents view, since both remain independently active/resumable.