feat: Enhance brush settings and add new layer paste functionality

- Added brush color variant and variant amount settings to the brush panel.
- Introduced a checkbox for color variant and a slider for variant amount in the brush settings.
- Implemented "Paste as New Layer" functionality, allowing users to paste clipboard images directly onto a new layer.
- Updated menus to include the new paste option with a shortcut.
- Improved layer panel iconography by replacing text buttons with SVG icons for visibility and lock toggles.
- Created new SVG assets for closed eye and watercolor icons.
- Enhanced history panel to provide richer descriptions for brush strokes and vector shape modifications.
- Fixed the issue where the first brush stroke was missing from the history panel.

hcie-iced-app/assets/icons/eye_closed.svg

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512" fill="currentColor">
+  <g transform="translate(40.96,40.96) scale(17.920000) translate(-0.00,-0.00)">
+    <path d="M12 6C5.6 6 1 12 1 12s4.6 6 11 6 11-6 11-6-4.6-6-11-6zm0 10c-2.2 0-4-1.8-4-4s1.8-4 4-4 4 1.8 4 4-1.8 4-4 4zm0-6.5c-1.4 0-2.5 1.1-2.5 2.5s1.1 2.5 2.5 2.5 2.5-1.1 2.5-2.5S13.4 9.5 12 9.5z"/>
+    <line x1="2" y1="2" x2="22" y2="22" stroke="currentColor" stroke-width="2.5" stroke-linecap="round"/>
+  </g>
+</svg>