style: redesign add/delete icons for modern UI consistency

Replace add.svg and delete.svg with minimalist design:
- 1.5px stroke width for thin, elegant appearance
- Round line caps and joins for smooth edges
- Consistent style across both icons
- Uses currentColor for theme compatibility

bricks/imgs/add.svg

@@ -1 +1,4 @@
-<svg t="1748765357426" class="icon" viewBox="0 0 1024 1024" version="1.1" xmlns="http://www.w3.org/2000/svg" p-id="42094" width="100%" height="100%"><path d="M512 512m-512 0a512 512 0 1 0 1024 0 512 512 0 1 0-1024 0Z" fill="currentColor" p-id="42095"></path><path d="M739.555556 568.888889H284.444444c-34.133333 0-56.888889-22.755556-56.888888-56.888889s22.755556-56.888889 56.888888-56.888889h455.111112c34.133333 0 56.888889 22.755556 56.888888 56.888889s-22.755556 56.888889-56.888888 56.888889z" fill="#FFFFFF" p-id="42096"></path><path d="M512 796.444444c-34.133333 0-56.888889-22.755556-56.888889-56.888888V284.444444c0-34.133333 22.755556-56.888889 56.888889-56.888888s56.888889 22.755556 56.888889 56.888888v455.111112c0 34.133333-22.755556 56.888889-56.888889 56.888888z" fill="#FFFFFF" p-id="42097"></path></svg>
+<svg width="24" height="24" viewBox="0 0 24 24" fill="none" xmlns="http://www.w3.org/2000/svg">
+  <circle cx="12" cy="12" r="10" stroke="currentColor" stroke-width="1.5"/>
+  <path d="M12 8v8M8 12h8" stroke="currentColor" stroke-width="1.5" stroke-linecap="round"/>
+</svg>

bricks/imgs/delete.svg

@@ -1 +1,4 @@
-<svg t="1748765552387" class="icon" viewBox="0 0 1024 1024" version="1.1" xmlns="http://www.w3.org/2000/svg" p-id="44745" width="100%" height="100%"><path d="M512 512m-481.882353 0a481.882353 481.882353 0 1 0 963.764706 0 481.882353 481.882353 0 1 0-963.764706 0Z" fill="currentColor" p-id="44746"></path><path d="M597.172706 542.117647l85.202823 85.172706a60.235294 60.235294 0 1 1-85.202823 85.202823L512 627.290353l-85.172706 85.202823a60.235294 60.235294 0 1 1-85.202823-85.202823L426.827294 542.117647l-85.202823-85.172706a60.235294 60.235294 0 1 1 85.202823-85.202823L512 456.944941l85.172706-85.202823a60.235294 60.235294 0 1 1 85.202823 85.202823L597.172706 542.117647z" fill="#FFFFFF" p-id="44747"></path></svg>
+<svg width="24" height="24" viewBox="0 0 24 24" fill="none" xmlns="http://www.w3.org/2000/svg">
+  <path d="M3 6h18M8 6V4a2 2 0 012-2h4a2 2 0 012 2v2M19 6l-1 14a2 2 0 01-2 2H8a2 2 0 01-2-2L5 6" stroke="currentColor" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round"/>
+  <path d="M10 11v6M14 11v6" stroke="currentColor" stroke-width="1.5" stroke-linecap="round"/>
+</svg>