fix: keep macOS status bar visible when switching Spaces

[jcbl1]

Problem

On macOS, the app runs as a tray-resident agent. After the main window is shown, switching to another desktop (Space) and back makes the entire system top menu bar / status bar (Apple menu, clock, battery, etc.) disappear, leaving blank space until the app loses focus.

Root cause

• The app runs as an ActivationPolicy.Accessory agent (LSUIElement=true): no Dock icon, no menu bar.
• The main window is a normal focusable window. When it lives on a Space that is switched away and back, macOS tries to draw a menu bar for the frontmost app. Since the app is accessory and has no menu bar, WindowServer fails to render it, and the whole status bar goes blank until another app is clicked.
• This is a systemic issue for LSUIElement/accessory apps + normal windows (same origin as Apple Feedback FB13544993).

Fix

Keep the app's activation policy consistent with main-window visibility, so the app is .regular whenever its window is shown:

Event	ActivationPolicy
Show main window (ShowMainWindow / tray Show / Cmd+S / second-instance launch)	.regular
Hide main window (HideMainWindow / Cmd+H / close button)	.accessory (back to tray-resident)
Startup	.regular or .accessory depending on StartHidden

• The fix follows the same approach used by DockDoor.
• As a side benefit, the app now also appears in and can be switched to via Cmd+Tab while its main window is visible.

Known tradeoff

A Dock icon is visible while the main window is shown and disappears when the window is hidden to the tray. So if it was a designed behaviour, this fix may not be proper.

[jcbl1]

Converted to draft as there are still some issue on Windows due to this fix.

[jcbl1]

Actually the fix has no effect on other OSs except extra emty bundles.

Meanwhile I found that in workflow config release.yml, there is an explicit command making the app . accessory, which was introduced in commit aa432e7 with message ci: Hide the Dock icon on macOS.. So it may be intentional to hide the Dock icon, which is reasonable as this app is a VPN app. However, the fix by this PR kind of respect the idea as it only shows Dock icon when the main window's open and thus introduces benefits such as Cmd+Tab switch when apps open and Cmd+W to close the main window. The Dock icon will disappear after closing/hiding the main window (yeah it's gone from the Dock), leaving an icon only on the menu bar.