Shader packs: the sky pass binds the pack's storage buffers

A sky program that reads the pack's SSBOs (Noble's gbuffers_textured, the fallback of
gbuffers_skytextured) was drawn without bind group 4: wgpu refused the frame ("expects a
BindGroup to be set at index 4") and the game panicked. The sky pass now binds them as the
other passes do.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

crates/horizon-client-render/src/gfx/pack_post.rs

@@ -2740,6 +2740,13 @@ impl PackPost {
                 let rp = &mut open.as_mut().expect("open").0;
                 rp.set_pipeline(pass.render());
                 rp.set_bind_group(0, group, &[]);
+                // A sky program that reads the pack's SSBOs (Noble's `gbuffers_textured`, the
+                // sun's fallback) binds them, as the other passes do.
+                if pass.buffers
+                    && let Some(g) = &self.buffers.group
+                {
+                    rp.set_bind_group(4, g, &[]);
+                }
                 sky.geometry.bind(rp, part.textured);
                 open.as_mut().expect("open").1 = i;
             }