Add a solid outline tracing the frame's outer edge

New plugin:hyprchrome:outline_size (px, 0 = off) and outline_color
(default white) stroke the frame's outer silhouette - chamfers, title bar
plateau and side notches - with a flat color, so it reads as a drawn line
against the gradient-filled frame underneath. Off by default.

The line sits inside the frame rather than centred on the silhouette. The
outer path runs along the texture's own bounds, so half of a centred
stroke would fall off the surface and vanish on exactly those sides;
stroking at double width leaves the inner half, which comes to
outline_size on every edge.

The clip is the whole ring rather than just the outer path, so an outline
thicker than the frame stops at the window's edge instead of spilling
across the ring onto the window, and a miter spike at the plateau's dip
stays confined to the frame.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/ChromeConfig.hpp

@@ -26,6 +26,14 @@ struct ChromeConfig {
   // border color's own alpha.
   SP<FloatValue> glowStrength;
 
+  // Thickness of the solid outline tracing the frame's edges, in logical
+  // pixels. 0 disables it entirely.
+  SP<IntValue> outlineSize;
+
+  // Color of that outline - a flat color rather than a gradient, so it reads
+  // as a drawn line against the gradient-filled frame it sits on.
+  SP<ColorValue> outlineColor;
+
   // How far the frame's drop shadow reaches past its own outline, in logical
   // pixels. 0 disables the shadow entirely.
   SP<IntValue> shadowSize;