Capture global hotkeys on Windows through raw input

A message-only window registers the keyboard and mouse with
RIDEV_INPUTSINK, so every key and button arrives as WM_INPUT whether or
not the client is in front. Raw input only observes, where a
WH_KEYBOARD_LL hook sits in the path of the system input queue and can
swallow a keystroke; it also reports the side buttons and both edges of
every key, which push-to-talk needs.

Keyboard codes stay in each platform's own numbering — X keycodes on
X11, set-1 scan codes with the E0/E1 escape folded into the high byte on
Windows — since that is what the input API reports and the key-naming
call expects. Bindings are per-machine either way, as TeamSpeak's own
per-OS keydefs are. Mouse buttons are unified on the X numbering, so
"Mouse 4" means the same thing on both.

The RAWINPUT decoding lives in its own class so it can be tested off
Windows; the window and its pump have not been run on Windows yet.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

ts3-client/desktop/src/test/java/com/ts3client/hotkey/desktop/RawInputTest.java

@@ -0,0 +1,92 @@
+package com.ts3client.hotkey.desktop;
+
+import com.ts3client.hotkey.HotkeyKey;
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/** Decoding of Windows raw input, which needs no Windows to check. */
+class RawInputTest {
+
+    @Test
+    void plainKeyKeepsItsScanCode() {
+        // 'A' is scan code 0x1E, no escape.
+        assertEquals(0x1E, RawInput.scanCode(0x1E, 0, 0x41));
+    }
+
+    @Test
+    void escapedKeysStayDistinctFromTheirUnescapedTwins() {
+        // Left Ctrl is 1D; right Ctrl is E0 1D, and the two must not collide.
+        int left = RawInput.scanCode(0x1D, 0, 0xA2);
+        int right = RawInput.scanCode(0x1D, RawInput.RI_KEY_E0, 0xA3);
+        assertEquals(0x1D, left);
+        assertEquals(0xE01D, right);
+    }
+
+    @Test
+    void pauseUsesTheOtherEscape() {
+        assertEquals(0xE11D, RawInput.scanCode(0x1D, RawInput.RI_KEY_E1, 0x13));
+    }
+
+    @Test
+    void fillerHalfOfAnEscapedSequenceIsIgnored() {
+        assertEquals(-1, RawInput.scanCode(0x2A, RawInput.RI_KEY_E0, 0xFF));
+        assertEquals(-1, RawInput.scanCode(0, 0, 0x41));
+    }
+
+    @Test
+    void breakFlagMarksTheRelease() {
+        assertFalse(RawInput.isRelease(0));
+        assertTrue(RawInput.isRelease(RawInput.RI_KEY_BREAK));
+        assertTrue(RawInput.isRelease(RawInput.RI_KEY_BREAK | RawInput.RI_KEY_E0));
+    }
+
+    @Test
+    void sideButtonsMapToTheNumbersUsersKnow() {
+        // X1 down: "Mouse 4" everywhere else in the client, X button 8.
+        List<RawInput.ButtonEvent> down = RawInput.buttons(0x0040, (short) 0);
+        assertEquals(List.of(new RawInput.ButtonEvent(HotkeyKey.mouse(8), true)), down);
+        assertEquals("Mouse 4", HotkeyKey.mouse(8).fallbackName());
+
+        List<RawInput.ButtonEvent> up = RawInput.buttons(0x0200, (short) 0);
+        assertEquals(List.of(new RawInput.ButtonEvent(HotkeyKey.mouse(9), false)), up);
+        assertEquals("Mouse 5", HotkeyKey.mouse(9).fallbackName());
+    }
+
+    @Test
+    void primaryButtonsUseTheXNumbering() {
+        assertEquals(List.of(new RawInput.ButtonEvent(HotkeyKey.mouse(1), true)),
+                RawInput.buttons(0x0001, (short) 0));
+        assertEquals(List.of(new RawInput.ButtonEvent(HotkeyKey.mouse(2), true)),
+                RawInput.buttons(0x0010, (short) 0));
+        assertEquals(List.of(new RawInput.ButtonEvent(HotkeyKey.mouse(3), true)),
+                RawInput.buttons(0x0004, (short) 0));
+    }
+
+    @Test
+    void oneEventCanCarrySeveralTransitions() {
+        // Left up and right down in the same report.
+        assertEquals(List.of(new RawInput.ButtonEvent(HotkeyKey.mouse(1), false),
+                        new RawInput.ButtonEvent(HotkeyKey.mouse(3), true)),
+                RawInput.buttons(0x0002 | 0x0004, (short) 0));
+    }
+
+    @Test
+    void wheelBecomesATapSoTheEngineSeesBothEdges() {
+        assertEquals(List.of(new RawInput.ButtonEvent(HotkeyKey.mouse(4), true),
+                        new RawInput.ButtonEvent(HotkeyKey.mouse(4), false)),
+                RawInput.buttons(0x0400, (short) 120));
+        assertEquals(List.of(new RawInput.ButtonEvent(HotkeyKey.mouse(5), true),
+                        new RawInput.ButtonEvent(HotkeyKey.mouse(5), false)),
+                RawInput.buttons(0x0400, (short) -120));
+    }
+
+    @Test
+    void mouseMovementAloneReportsNothing() {
+        assertEquals(List.of(), RawInput.buttons(0, (short) 0));
+    }
+}