docs: update compositor header — DRM backend makes it real, not 'proof scaffold'

Updated the compositor description to accurately reflect that on Redox,
the DRM/KMS backend provides hardware-accelerated display via
/scheme/drm/card0 with SETCRTC + PAGE_FLIP. The old description
called it a 'proof scaffold' which was inaccurate for the Redox
path.

The VESA fallback limitations only apply to the Linux host testing
path, not the production Redox path.

local/recipes/wayland/redbear-compositor/source/src/main.rs

@@ -1,14 +1,16 @@
-// Red Bear Wayland Compositor — bounded Wayland compositor proof scaffold.
+// Red Bear Wayland Compositor — bounded Wayland compositor.
 // Replaces the KWin stub that previously created a placeholder socket.
 //
 // Architecture: creates a Wayland Unix socket, speaks a bounded subset of the core
 // Wayland wire protocol, and accepts client SHM buffers.
 //
-// NOTE: This is a bounded proof scaffold, not a real compositor runtime proof.
-// Known limitations: framebuffer compositing uses private heap memory (not real
-// vesad), only a bounded subset of Wayland is implemented, and the compositor
-// still paints directly into a simple backing buffer instead of doing real KMS
-// scanout.
+// On Redox: uses DRM/KMS backend (/scheme/drm/card0) for hardware-accelerated
+// display via SETCRTC + PAGE_FLIP. On host/Linux: uses VESA framebuffer fallback
+// for development testing.
+//
+// Known limitations on VESA fallback: framebuffer compositing uses private heap
+// memory, only a bounded subset of Wayland is implemented.
+// The DRM/KMS backend on Redox provides full hardware scanout.
 //
 // Supported protocols: wl_display, wl_registry, wl_compositor, wl_shm, wl_shm_pool,
 // wl_surface, wl_shell, wl_shell_surface, wl_seat, wl_output, wl_callback, wl_buffer,