feat: add type-safe native platform headers and portable drag support

- Add include/yasl/native/{wayland,cocoa,x11}.h with type-safe handle accessors.
- Unify drag-and-drop and window carry support across Wayland, X11, and Cocoa.
- Preserve full ABI compatibility for capability flags.
- Install native headers conditionally based on enabled backend.
- Include missing tablet example and backend test suites.

1 files changed, 36 insertions, 0 deletions

diff --git a/src/common/native.c b/src/common/native.c
index 2d9c06f..6e1c69a 100644
--- a/src/common/native.c
+++ b/src/common/native.c
@@ -1,5 +1,13 @@
 #include "backend.h"
 
+#if YASL_HAS_WAYLAND
+#include "yasl/native/wayland.h"
+#endif
+
+#if YASL_HAS_X11
+#include "yasl/native/x11.h"
+#endif
+
 #include <errno.h>
 
 void *yasl_display_get_native_handle(struct yasl_display *d)
@@ -14,6 +22,34 @@ void *yasl_surface_get_native_handle(struct yasl_surface *s)
         s->display->ops->surface_get_native_handle(s) : NULL;
 }
 
+#if YASL_HAS_WAYLAND
+struct wl_display *yasl_wayland_display_get_wl_display(struct yasl_display *d)
+{
+    return (d && yasl_display_backend(d) == YASL_BACKEND_WAYLAND) ?
+        (struct wl_display *)yasl_display_get_native_handle(d) : NULL;
+}
+
+struct wl_surface *yasl_wayland_surface_get_wl_surface(struct yasl_surface *s)
+{
+    return (s && s->display && yasl_display_backend(s->display) == YASL_BACKEND_WAYLAND) ?
+        (struct wl_surface *)yasl_surface_get_native_handle(s) : NULL;
+}
+#endif
+
+#if YASL_HAS_X11
+Display *yasl_x11_display_get_display(struct yasl_display *d)
+{
+    return (d && yasl_display_backend(d) == YASL_BACKEND_X11) ?
+        (Display *)yasl_display_get_native_handle(d) : NULL;
+}
+
+uintptr_t yasl_x11_surface_get_window(struct yasl_surface *s)
+{
+    return (s && s->display && yasl_display_backend(s->display) == YASL_BACKEND_X11) ?
+        (uintptr_t)yasl_surface_get_native_handle(s) : 0;
+}
+#endif
+
 struct yasl_surface *yasl_surface_create_native(struct yasl_display *d,
         const struct yasl_surface_spec *spec, void *graphics_device)
 {