[Bug] claude agents: session-name column is fixed-narrow and truncates names even on wide terminals

What happens

The claude agents list renders the first column (session name) at a fixed, narrow width. It doesn't grow to use available terminal width, even on a very wide display, so long session names are truncated — while the rest of the row sits in empty space.

Why it's a problem

The name is the main way to tell sessions apart. When truncated, multiple distinct sessions show the same visible prefix (e.g. feat/core-simulation-impl…), so I can't navigate the list. This also makes /rename pointless — a descriptive name I set gets cut off.

Expected

The name column should use the wasted horizontal space — e.g. expand to fit the longest name, absorb remaining terminal width, or be configurable (a settings.json width option). At minimum it should grow with terminal width instead of staying fixed.

Steps to reproduce

1. Have a few sessions with long names (or /rename some to long names).
2. Open claude agents in a wide (e.g. 200+ col) terminal.
3. Note the name column stays narrow and truncates, despite ample empty space to the right.

Environment

• Platform: darwin · Terminal: xterm-256color · Version: 2.1.158
• Feedback ID: ac70f963-0131-4ddf-8cc5-a4997fb2e34c