Add option to keep keyboard hidden in mouse mode

[alexy]

Summary

• add a Keep Keyboard Hidden setting for terminal programs using VT mouse reporting
• preserve the current tap-to-focus behavior by leaving the setting off by default
• let a two-finger tap explicitly restore keyboard focus while mouse reporting is active
• expose the preference as keep_keyboard_hidden_in_mouse_mode through /proc/ish/defaults

Motivation

Full-screen terminal applications such as Emacs use mouse events for controls. iSH currently asks the native view to become first responder after every terminal tap, so tapping a control immediately reopens a software keyboard that the user deliberately hid. With this option enabled, mouse-aware applications receive the tap without also showing the keyboard.

Testing

• node --check app/terminal/term.js
• unsigned generic iOS build with Debug-ApplePleaseFixFB19282108
• signed device build installed over an existing app container
• verified the Settings storyboard compiles and links with the new outlet/action
• manually verified the original behavior before converting it to a persisted toggle: one-finger mouse-mode taps keep the keyboard hidden, two-finger tap restores it, and ordinary terminal taps still focus outside mouse mode