style: replace raw colors.css refs with glass tokens from constant.css

Replace @foreground, @primary, @error, @outline, @shadow, @secondary
and their var() equivalents with semantic glass-* tokens across 22 files.
Colors without glass equivalents (@on-primary, @cyan, etc.) left as-is.

src/styles/window/lock.css

@@ -7,14 +7,14 @@
 }
 
 #lock-notch-stack {
-    background-color: @shadow;
+    background-color: @glass-overlay-dark;
     border-radius: 0 0 apply(radius-lg) apply(radius-lg);
     min-width: 200px;
     min-height: 34px;
 }
 
 #lock-notch-corner {
-    background-color: @shadow;
+    background-color: @glass-overlay-dark;
     border-radius: 0;
     min-width: 20px;
     min-height: 20px;