Skybox image: power-of-two resize; upload at FRAME_RENDER_START

- The material system rejects textures whose dimensions are not multiples of 4
  ("Image dimensions must be multiple of 4!"), so scale the decoded image to
  the next power of two (bilinear). 798x798 -> 1024x1024. The invalid VTF also
  crashed the renderer after the apply.
- Move skybox_update() out of the VGUI paint hook into the FRAME_RENDER_START
  FrameStageNotify stage. ITexture::Download only regenerates bits when the
  material system considers the frame render-safe; during paint it returned
  early, the regenerator never ran (no pixels), and a later upload of the
  empty VTF crashed.
- Log the regenerator entry so the log shows whether the upload path ran.

1 files changed, 0 insertions, 1 deletions

diff --git a/src/menu.cpp b/src/menu.cpp
index 92131d4..7ffc84a 100644
--- a/src/menu.cpp
+++ b/src/menu.cpp
@@ -816,7 +816,6 @@ void outer_draw() {
   fullbright_update();
   world_tint_update();
   fog_update();
-  skybox_update();
   gui_handle_input();
   // HL2H_DRAW_TEST=1 draws a probe rect without needing the GUI open
   static bool draw_test = getenv("HL2H_DRAW_TEST") != nullptr;