Allow notification sounds to play in the focused workspace (or add an opt-in to ignore focus suppression)

[CarlSchader]

Currently ui.sound.enabled is documented as playing sounds only when agents change state in background workspaces ("Play sounds when agents change state in background workspaces"). I'd like an option to also play the notification sound when the state change happens in the currently focused pane/workspace.

Use case

I'm often working inside a pane that's running an agent (reading output / typing the next prompt while it works), and I still want the done / needs-attention audio cue. The sound tells me the agent finished a step even though I'm already looking at that pane.

Suggested config

[ui.sound]
enabled = true
play_when_focused = true   # new option — lift the background-only restriction

…or a simpler boolean that lifts the background-only restriction.

Related

• The other sound keys (ui.sound.path, ui.sound.done_path, ui.sound.request_path, and per-agent overrides like ui.sound.agents.claude) only change which sound plays or disable it for specific agents — they don't change when sounds fire.
• Agent state sounds play for the focused pane in the focused workspace (docs say background workspaces only) #2571 reported that sounds do currently fire for the focused pane (contradicting the docs) and was redirected here for feature discussion. I'd like this to be an explicit, opt-in option rather than relying on undocumented behavior.

Environment

• herdr 0.9.1
• macOS