Inject Remote lock keys instead of retiring keyboard input

Refusing Caps, Num and Scroll Lock retired all remote input, so a
controller using Caps Lock as its screen-reader modifier lost keyboard
control on the first press. Lock keys are now owned like other keys and
released once at retirement without another toggle.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/platform/xorg/remote_keys_native_test.go

@@ -200,8 +200,30 @@ func TestNativeRemoteKeyTargetLayoutChangeKeepsRelease(t *testing.T) {
 	remoteNativeHeld(t, probe, after, false)
 }
 
-func TestNativeRemoteKeyTargetRejectsUnavailableAndLocks(t *testing.T) {
-	for _, name := range []string{"unknown private name", "Caps_Lock", "Num_Lock", "Scroll_Lock", "semicolon"} {
+func TestNativeRemoteKeyTargetLockKeysAreOwnedAndReleased(t *testing.T) {
+	for _, name := range []string{"Caps_Lock", "Num_Lock", "Scroll_Lock"} {
+		t.Run(name, func(t *testing.T) {
+			remoteNativeThread(t)
+			target, probe := remoteNativeTarget(t), remoteNativeTarget(t)
+			code, err := target.backend.Resolve(name)
+			if err != nil {
+				t.Skip("lock key absent from this keymap")
+			}
+			if err := target.apply(name, true); err != nil {
+				t.Fatal("lock key refused", err)
+			}
+			remoteNativeHeld(t, probe, code, true)
+			// Retirement releases the held lock key without another toggle.
+			if err := target.retire(); err != nil {
+				t.Fatal(err)
+			}
+			remoteNativeHeld(t, probe, code, false)
+		})
+	}
+}
+
+func TestNativeRemoteKeyTargetRejectsUnavailable(t *testing.T) {
+	for _, name := range []string{"unknown private name", "semicolon"} {
 		t.Run(name, func(t *testing.T) {
 			remoteNativeThread(t)
 			target, probe := remoteNativeTarget(t), remoteNativeTarget(t)