Add Right Alt+C/V → Cmd+C/V mapping for Mac streaming

[dangnm]

Summary

When streaming to a Mac via Sunshine, the Command key is not directly accessible from Android keyboards. This PR adds a preference that fully remaps the Right Alt key to Command for Mac streaming.

• Adds a new opt-in preference "Right Alt as Command (Mac)" under keyboard settings (disabled by default)
• When enabled, Right Alt behaves exactly like the Command key — any Right Alt+key combo becomes Command+key (e.g. Right Alt+C = Cmd+C, Right Alt+Z = Cmd+Z, Right Alt+Tab = Cmd+Tab)
• Left Alt is completely unaffected
• International keyboard users (e.g. Polish AltGr combos) are not impacted as the feature is disabled by default
• Fixes a related bug where the backAsMeta preference did not update the internal modifier state, causing subsequent keys to miss the Meta modifier

How it works

When Right Alt is pressed with the preference enabled:

1. handleSpecialKeys() intercepts the key event and sends VK_LWIN (mapped to Command on macOS by Sunshine) instead of VK_RMENU
2. modifierFlags is updated with MODIFIER_META instead of MODIFIER_ALT
3. getModifierState() is patched to suppress MODIFIER_ALT from Android's key event meta state when Right Alt is the only Alt held, preventing spurious Alt+Command combos from reaching the host

Files changed

• Game.java — Right Alt → Command remapping in handleSpecialKeys(), modifier state fix in getModifierState(), backAsMeta modifier flag fix
• PreferenceConfiguration.java — new rightAltAsMeta preference field
• preferences.xml — new CheckBoxPreference entry
• strings.xml — new preference title and summary strings

[ClassicOldSong]

Thank you, but why not make right alt meta directly?

[kayti]

Thank you, but why not make right alt meta directly?

Right Alt is often used with special characters in many languages, e.g., Polish R ALT+A gives ą, etc. So directly mapping it would be problematic for some.

[dangnm]

Thank you, but why not make right alt meta directly?

Right Alt is often used with special characters in many languages, e.g., Polish R ALT+A gives ą, etc. So directly mapping it would be problematic for some.

This is opt-in and disabled by default. The preference Right Alt as Command (Mac) must be explicitly enabled by the user. Polish and other international keyboard users are unaffected unless they choose to enable it.

[dangnm]

Thank you, but why not make right alt meta directly?

Done. Right Alt is now fully remapped to Command when the preference is enabled, not just for C/V. Any Right Alt+key combo (e.g. Right Alt+Z for Cmd+Z, Right Alt+Tab for Cmd+Tab) will work as expected.