build: drop the bytemuck declaration this crate never used

Leftovers from the retired wgpu rendering path. Nothing in this crate
names bytemuck — not in src/, tests, or a build script. cce-ui renders
with raw Vulkan via ash, and clients only ever hand it display lists.

Manifest hygiene rather than a build-time saving: both still compile as
transitive dependencies (wgpu via glyphon, bytemuck via cce-ui and image
among others). What goes away is the false claim that this crate talks
to a GPU API directly.

Part of a workspace-wide sweep of the same dead declarations, which sat
in 13 crates (wgpu) and 14 (bytemuck). cce-designer and cce-ui keep
bytemuck — they genuinely use it.

 Cargo.toml | 1 -
 1 file changed, 1 deletion(-)

diff --git a/Cargo.toml b/Cargo.toml
index 64f2dd2..e5b86ab 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -11,7 +11,6 @@ calloop-wayland-source = "0.3.0"
 wayland-client = { version = "0.31", features = ["system"] }
 xkeysym = "0.2"
 raw-window-handle = "0.6"
-bytemuck = { version = "1", features = ["derive"] }
 # glyphon supplies cosmic-text/swash shaping for the cce_ui::vk text stage.
 glyphon = "0.8"
 serde = { version = "1.0", features = ["derive"] }