Agents window chat tab shortcuts override terminal tabs

Does this issue occur when all extensions are disabled?: Yes

- VS Code Version: 1.137.0
- OS Version: macOS 26.6.2

Steps to Reproduce:

1. Open the Agents window.
2. Open multiple chat tabs and terminal tabs.
3. Focus the terminal.
4. Press `Cmd+Shift+[` or `Cmd+Shift+]`.

The active chat changes instead of the terminal tab.

#332029 removed these shortcuts from session navigation. Chat navigation still uses them.