[client] egl: make native HDR encoding-safe

Request true floating-point EGL configs for scRGB and expose the native
encodings supported by the selected surface. Fall back to software HDR
mapping when the surface cannot represent the incoming wire format.

Resample PQ in linear light, keep SDR-only effects out of native PQ
chains, and consume the cursor-specific white level without changing
binary monochrome cursor mask operations.

client/include/interface/renderer.h

@@ -52,7 +52,9 @@ LG_RendererParams;
 
 typedef enum LG_RendererSupport
 {
-  LG_SUPPORTS_DMABUF
+  LG_SUPPORTS_DMABUF,
+  LG_SUPPORTS_HDR_PQ,
+  LG_SUPPORTS_HDR_SCRGB
 }
 LG_RendererSupport;
 
@@ -163,6 +165,10 @@ typedef struct LG_RendererOps
   void (*onMouseColorTransform)(LG_Renderer * renderer,
       const KVMFRColorTransform * transform);
 
+  /* updates the cursor-specific SDR white level reported by IddCx
+   * Context: cursorThread */
+  void (*onMouseWhiteLevel)(LG_Renderer * renderer, uint32_t sdrWhiteLevel);
+
   /* called when the mouse has moved or changed visibillity
    * Context: cursorThread */
   bool (*onMouseEvent)(LG_Renderer * renderer, const bool visible, int x, int y,