Idea: hidden JSON-only setting to hide the macOS Dock icon

[unveroleone]

Moving this over from #2392 as requested.

What happens today

On macOS, Handy only runs as an accessory app (no Dock icon) when it starts hidden and the tray icon is enabled. If show_tray_icon is false, the Dock icon stays visible even with start_hidden: true — so there is currently no way to run Handy fully invisibly in the background.

Handy is a hotkey-driven tool: the window is rarely opened, so leaving a permanent Dock presence for an app you interact with via fn+dictation feels heavier than it needs to be.

Proposal

@cjpais suggested this would only be mergeable as a hidden setting in the JSON file, not exposed in the UI, to avoid confusing users. That sounds like exactly the right shape:

• Add something like hide_dock_icon: false (default off) to settings_store.json
• When enabled on macOS, switch the NSApplication activation policy to .accessory at startup, independent of the tray icon
• Document it in the settings reference only, not the UI

No new UI surface, no change for anyone who doesn't edit the file, and the tray icon behaviour stays exactly as-is for everyone else.

Question for the community

Would you use this? If there's interest, it's a small, self-contained macOS-only change. If it turns out nobody wants it, that's a clear signal too.