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/ChromePassElement.cpp

@@ -75,7 +75,10 @@ std::vector<UP<IPassElement>> ChromePassElement::draw() {
   // with title length - otherwise every title change would needlessly
   // regenerate an identical border texture.
   const float borderTitleBarWidthPx = geo.fullSpan ? geo.MaxTitleBarWidth() : geo.titleBarWidth;
-  const auto tex = data.decoration->GetBorderTexture({box.w, box.h}, extentPx, chamferPx, gradient, titleBarHeightPx, borderTitleBarWidthPx, glowPx, glowStrength);
+  const float outlinePx = static_cast<float>(PluginState->config.outlineSize->value()) * monitor->m_scale;
+  const CHyprColor outlineColor{static_cast<uint64_t>(PluginState->config.outlineColor->value())};
+
+  const auto tex = data.decoration->GetBorderTexture({box.w, box.h}, extentPx, chamferPx, gradient, titleBarHeightPx, borderTitleBarWidthPx, glowPx, glowStrength, outlinePx, outlineColor);
   if (!tex || !tex->ok())
     return {};