perf(k-ui): own pixel loops (pixels.rs): float only in corners, SWAR blends, banded shadow; screen fade only over content toward wallpaper (was full-window tiny-skia fill, ~600ms); blur at quarter res, row/column-sum passes, SWAR 2x upscale; ring frame ~75 -> ~20ms

crates/k-ui/src/lib.rs

@@ -11,6 +11,7 @@ extern crate alloc;
 pub mod element;
 pub mod glass;
 pub mod layout;
+mod pixels;
 pub mod motion;
 pub mod render;
 pub mod run;