[client] transport: introduce pluggable frame transports

Move shared-memory ownership, LGMP session handling, queue access, and
DMA setup behind a transport interface. The LGMP backend preserves the
existing zero-copy frame and DMA paths while owning its lgmp:* options.

Expose the initialized EGL context through a versioned renderer interop
record for future accelerated decode backends. Add an LGMP-independent,
deterministic test transport for graphics-pipeline validation.

client/renderers/EGL/damage.h

@@ -21,14 +21,14 @@
 #pragma once
 
 #include <stdbool.h>
-#include "common/KVMFR.h"
+#include "common/types.h"
 #include "interface/renderer.h"
 #include "desktop_rects.h"
 
 struct DesktopDamage
 {
   int count;
-  FrameDamageRect rects[KVMFR_MAX_DAMAGE_RECTS];
+  FrameDamageRect rects[LG_MAX_FRAME_DAMAGE_RECTS];
 };
 
 typedef struct EGL_Damage EGL_Damage;