Android: final refinements per maintainer feedback

- Change database migration to use BOOLEAN instead of INTEGER for sendRawKeys
- Remove useExtended field, use only OptionalInt.isPresent() for cleaner design
- Add authoritative specification links: RFC 6143 for RFB protocol and vncdotool for QEMU Extended Key Event protocol
- Simplify OutputEvent constructor by removing useExtended parameter

All changes compile successfully. Addresses final review comments from PR bk138#272.

Author: SashankBhamidi

android/app/src/main/java/com/coboltforge/dontmind/multivnc/AndroidKeyToXt.kt

@@ -11,6 +11,8 @@ import android.view.KeyEvent
  * For 2-byte XT codes (like arrow keys), we encode them as single integers
  * where the high byte represents the 0xe0 prefix.
  *
+ * RFB Protocol (RFC 6143): https://www.rfc-editor.org/rfc/rfc6143.html
+ * QEMU Extended Key Event protocol: https://vncdotool.readthedocs.io/en/78/rfbproto.html
  * XT scan code specification: https://www.win.tue.nl/~aeb/linux/kbd/scancodes-1.html
  */
 object AndroidKeyToXt {

android/app/src/main/java/com/coboltforge/dontmind/multivnc/VNCConn.java

@@ -111,17 +111,16 @@ public OutputEvent(int x, int y, int modifiers, int pointerMask) {
     		pointer.mask = pointerMask;
     	}
 
-    	public OutputEvent(int keyCode, int metaState, boolean down, OptionalInt xtKeycode, boolean useExtended) {
+    	public OutputEvent(int keyCode, int metaState, boolean down, OptionalInt xtKeycode) {
     		key = new KeyboardEvent();
     		key.keyCode = keyCode;
     		key.metaState = metaState;
     		key.down = down;
     		key.xtKeycode = xtKeycode;
-    		key.useExtended = useExtended;
     	}
 
     	public OutputEvent(int keyCode, int metaState, boolean down) {
-    		this(keyCode, metaState, down, OptionalInt.empty(), false);
+    		this(keyCode, metaState, down, OptionalInt.empty());
     	}
 
     	public OutputEvent(boolean incremental) {
@@ -155,7 +154,6 @@ private class KeyboardEvent {
     		int metaState;
     		boolean down;
     		OptionalInt xtKeycode;  // XT scancode for extended key events
-    		boolean useExtended;  // whether to use extended key events
     	}
 
     	private class FullFramebufferUpdateRequest {
@@ -377,7 +375,7 @@ private boolean sendKeyEvent(OutputEvent.KeyboardEvent evt) {
 				   if(Utils.DEBUG()) Log.d(TAG, "sending key " + evt.keyCode + (evt.down?" down":" up"));
 
 				   // Use extended key event if available and enabled
-				   if (evt.useExtended && evt.xtKeycode.isPresent() && rfbSupportsExtendedKeys()) {
+				   if (evt.xtKeycode.isPresent() && rfbSupportsExtendedKeys()) {
 					   if(Utils.DEBUG()) Log.d(TAG, "sending extended key: keysym=0x" + Integer.toHexString(evt.keyCode) +
 						   ", xtCode=0x" + Integer.toHexString(evt.xtKeycode.getAsInt()) + (evt.down?" down":" up"));
 					   rfbSendExtendedKeyEvent(evt.keyCode, evt.xtKeycode.getAsInt(), evt.down);
@@ -629,15 +627,13 @@ public boolean sendKeyEvent(int keyCode, KeyEvent evt, boolean sendDirectly) {
 				}
 
 				// Check if we should use extended key events
-				boolean useExtended = false;
 				OptionalInt xtKeycode = OptionalInt.empty();
 
 				if (connSettings != null && connSettings.sendRawKeys && !sendDirectly) {
 					int xtCode = AndroidKeyToXt.INSTANCE.getXtKeycode(evt.getKeyCode());
 					// Only use extended keys if we have a valid XT mapping
 					if (xtCode != 0) {
 						xtKeycode = OptionalInt.of(xtCode);
-						useExtended = true;
 						if(Utils.DEBUG()) {
 							Log.d(TAG, "Using extended key event: keyCode=" + evt.getKeyCode() +
 								" -> keysym=0x" + Integer.toHexString(keyCode) +
@@ -650,8 +646,7 @@ public boolean sendKeyEvent(int keyCode, KeyEvent evt, boolean sendDirectly) {
 						keyCode,
 						metaState,
 						evt.getAction() == KeyEvent.ACTION_DOWN,
-						xtKeycode,
-						useExtended);
+						xtKeycode);
 				outputEventQueue.add(e);
 				synchronized (outputEventQueue) {
 					outputEventQueue.notify();

android/app/src/main/java/com/coboltforge/dontmind/multivnc/db/VncDatabase.java

@@ -174,8 +174,8 @@ public void migrate(@NonNull SupportSQLiteDatabase database) {
         public void migrate(@NonNull SupportSQLiteDatabase database) {
             Log.i("VncDatabase", "Migrating to Room [15 -> 16]");
 
-            // add new SENDRAWKEYS column to CONNECTION_BEAN with default value false (0)
-            database.execSQL("ALTER TABLE CONNECTION_BEAN ADD SENDRAWKEYS INTEGER NOT NULL DEFAULT 0");
+            // add new SENDRAWKEYS column to CONNECTION_BEAN with default value false
+            database.execSQL("ALTER TABLE CONNECTION_BEAN ADD SENDRAWKEYS BOOLEAN NOT NULL DEFAULT FALSE");
         }
     };
 }