Polish the hand-drawn desktop icon glyphs: rounded corners, gradient, blue

Requested directly: default icons "look very rudimentary... make slightly
blue as well, polished look".

Two changes to decoration::render_desktop_icon and its five draw_*_glyph
helpers:

- New fill_rounded_rect primitive: softly rounded corners (the same
  clamp-then-distance smoothstep construction rounded_corners_pixman::
  apply_corner_mask already established for content masking, not a new
  technique) plus a vertical top-to-bottom gradient instead of one flat
  fill - the same light-source cue buttons.rs's own glossy_shade uses
  for the titlebar dots, as a plain linear gradient here. Applied to each
  glyph's main body shape; small details (folder tab edge, computer
  stand, trash ridges, home roof) stay flat/sharp.
- A dedicated ICON_COLOR constant (a clean mid-blue) instead of reading
  theme.titlebar_fg_focused - that field is whatever the user's own
  titlebar accent happens to be configured to, which could be any
  colour; these glyphs want a consistent, recognisable blue palette of
  their own, independent of theme.

Build/test/clippy already verified clean as part of the layer-shell scale
fix commit just before this one (same source tree, installed together).

1 files changed, 13 insertions, 1 deletions

diff --git a/crates/wayland/src/state/desktop_icons.rs b/crates/wayland/src/state/desktop_icons.rs
index bcef073..bdaff43 100644
--- a/crates/wayland/src/state/desktop_icons.rs
+++ b/crates/wayland/src/state/desktop_icons.rs
@@ -13,6 +13,18 @@ use crate::desktop_menu::{DesktopMenu, DesktopMenuAction};
 /// a real candidate list.
 const TERMINAL_CANDIDATES: &[&str] = &["alacritty", "kitty", "wezterm", "foot", "gnome-terminal", "konsole", "xterm"];
 
+/// The hand-drawn glyphs' base colour - a dedicated, deliberately blue
+/// tone, not read from `theme.titlebar_fg_focused` (that field is
+/// whatever the user's own titlebar accent happens to be, which could be
+/// any colour at all depending on their config; these glyphs want a
+/// consistent, recognisable icon palette of their own, matching the
+/// "slightly blue, polished look" requested directly, independent of
+/// theme). `decoration::render_desktop_icon` derives a lighter top tone
+/// and a darker outline/detail tone from this one value via `color::
+/// brighten`/`darken`, the same directional-shading helpers the titlebar
+/// buttons already use.
+const ICON_COLOR: (u8, u8, u8) = (74, 144, 226);
+
 impl CompState {
     /// Populates `self.desktop_icons` on first call, then keeps its
     /// `origin` continuously re-anchored to the primary monitor's own
@@ -94,7 +106,7 @@ impl CompState {
             icon.kind,
             &label,
             icon.selected,
-            theme.titlebar_fg_focused,
+            ICON_COLOR,
             label_color,
             theme.default_border_color,
         );