app: true 10-bit presentation -- F32 frames reach the swapchain unquantized

The display path no longer passes through BGRA8: render workers are
asked for F32, rows are repacked, colour management runs on the F32
data, and the frame uploads to an Rgba16Float wgpu texture that the
viewer presents directly on the Rgb10a2Unorm swapchain. The BGRA8
image remains only for scopes, the eyedropper, thumbnails and the
no-GPU fallback.

Cargo.lock

@@ -4727,6 +4727,7 @@ dependencies = [
  "gpui_elements",
  "gpui_platform",
  "gpui_widgets",
+ "half",
  "image",
  "oak-audio",
  "oak-codec",
@@ -4741,6 +4742,7 @@ dependencies = [
  "oak-undo",
  "serde_yaml",
  "smallvec",
+ "wgpu 29.0.4",
 ]
 
 [[package]]