[idd] input: add mouse and keyboard IPC messages

Replace raw HID report forwarding with typed absolute mouse, relative
mouse, and keyboard messages.

Expose absolute and relative modes as separate Mouse collections because
Windows MouHID requires one X/Y motion mode per mouse device.

idd/LGIdd/ipc/CInputPipeServer.h

@@ -21,6 +21,7 @@
 #pragma once
 
 #include "CPipeEndpoint.h"
+#include "InputPipeProtocol.h"
 
 #include <stddef.h>
 #include <stdint.h>
@@ -33,12 +34,29 @@ public:
   bool Init();
   void DeInit();
 
-  bool SendReport(
-    _In_reads_bytes_(size) const void * report,
-    _In_ size_t size);
+  // Mouse buttons use LGInputMouseButton bits. Wheel values are -127..127.
+  bool SendMouseRelative(
+    _In_ int16_t deltaX,
+    _In_ int16_t deltaY,
+    _In_ int8_t wheel,
+    _In_ uint8_t buttons);
+  // Absolute coordinates are normalized to 0..32767 on each axis.
+  bool SendMouseAbsolute(
+    _In_range_(0, LG_INPUT_MOUSE_ABSOLUTE_MAX) uint16_t x,
+    _In_range_(0, LG_INPUT_MOUSE_ABSOLUTE_MAX) uint16_t y,
+    _In_ int8_t wheel,
+    _In_ uint8_t buttons);
+  // Keys are USB HID Keyboard/Keypad usage IDs; zero marks an empty slot.
+  bool SendKeyboard(
+    _In_ uint8_t modifiers,
+    _In_reads_(LG_INPUT_KEYBOARD_KEY_COUNT) const uint8_t * keys);
   bool IsConnected() const { return m_endpoint.IsConnected(); }
 
 private:
+  bool SendMessage(
+    _In_ LGInputPipeMessageType type,
+    _In_reads_bytes_(size) const void * payload,
+    _In_ size_t size);
   bool OnPipeMessage(const void * message, size_t size) override;
 
   CPipeEndpoint m_endpoint;