perf(agc): combine consecutive descriptor set binds - #11

What

Split graphics resources bind descriptor sets 0 and 1 with two vkCmdBindDescriptorSets calls. Bind the two consecutive sets in one call when both exist, preserving set order, handles, bind point, and pipeline layout. Main-only, fragment-only, and empty cases retain their behavior. Use the same helper for ordinary resources and per-draw snapshot bindings.

The current refresh preserves main’s image-descriptor mock handling and all image-table tests. The helper statically requires the fragment descriptor set to remain set 1.

Tested

Refreshed as one commit on main 763ad20fc19. Release builds of the graphics and draw-cache-reuse tests pass. Both executables pass on RADV/Radeon and lavapipe: four invocations passed, no whole-test skips. The graphics suite includes the split-resource bind assertions for two sets, each single set, and no sets. Heap-mirror subchecks report unavailable without a write-watched guest arena and are not counted as validated.

Conventions and whitespace checks pass. No matched title performance comparison, Windows build, or full-suite run has been completed on this refresh. The reduced command count does not establish a gameplay FPS improvement.

Checklist

• One topic; generic descriptor binding
• No code comments, assets, or new dependencies
• Existing image-descriptor and image-table tests preserved
• Depends on: none
• Unblocks: none
• GPUs tested: AMD Radeon RX 6650 XT, RADV Mesa 26.2.4, Linux; lavapipe Mesa 26.2.4 on the same Linux host
• AI-assisted: yes