feat: add keyboard layout support

kernel/src/Drivers/PS2/Keyboard.hpp

@@ -18,6 +18,13 @@ namespace Drivers::PS2::Keyboard {
         bool    Ctrl;
         bool    Alt;
         bool    CapsLock;
+        // Right Alt held. Reported separately from Alt so keyboard layouts can
+        // use it as AltGr without swallowing left-Alt shortcuts.
+        bool    AltGr;
+        // Key came from an E0-prefixed (extended) scancode. The prefix is not
+        // part of Scancode, so without this flag keypad "/" is indistinguishable
+        // from the main "/" key and layout translation would rewrite it.
+        bool    Extended;
     };
 
     // Modifier key state
@@ -52,4 +59,8 @@ namespace Drivers::PS2::Keyboard {
     // Inject a key event from an external source (e.g., USB HID keyboard)
     void InjectKeyEvent(const KeyEvent& event);
 
+    // Current Caps Lock state. Injecting drivers (USB HID) need this to
+    // compute ASCII, since the lock is toggled centrally here.
+    bool GetCapsLock();
+
 };