[client] clipboard: add transport provider interface

Route clipboard exchange through a provider interface. Connected
transports take priority while SPICE remains the fallback.

Track asynchronous X11 and Wayland transfers by request, preserving
clipboard ownership across provider changes.

Use PureSpice clipboard status notifications for capability and
lifecycle updates.

client/include/interface/displayserver.h

@@ -26,18 +26,7 @@
 #include <EGL/egl.h>
 #include "common/types.h"
 #include "common/debug.h"
-
-typedef enum LG_ClipboardData
-{
-  LG_CLIPBOARD_DATA_TEXT = 0,
-  LG_CLIPBOARD_DATA_PNG,
-  LG_CLIPBOARD_DATA_BMP,
-  LG_CLIPBOARD_DATA_TIFF,
-  LG_CLIPBOARD_DATA_JPEG,
-
-  LG_CLIPBOARD_DATA_NONE // enum max, not a data type
-}
-LG_ClipboardData;
+#include "interface/clipboard.h"
 
 typedef enum LG_DSProperty
 {
@@ -136,9 +125,6 @@ typedef struct LG_DSInitParams
 }
 LG_DSInitParams;
 
-typedef void (* LG_ClipboardReplyFn)(void * opaque, const LG_ClipboardData type,
-    uint8_t * data, uint32_t size);
-
 typedef struct LG_DSGLContext
   * LG_DSGLContext;
 
@@ -262,7 +248,7 @@ struct LG_DisplayServerOps
   bool (*cbInit)(void);
   void (*cbNotice)(LG_ClipboardData type);
   void (*cbRelease)(void);
-  void (*cbRequest)(LG_ClipboardData type);
+  void (*cbRequest)(LG_ClipboardRequest request, LG_ClipboardData type);
 };
 
 #ifdef ENABLE_EGL