Add item icon art for all 41 item types

Self-contained full-color SVGs in data/icons/items/, one per item id, read
by the recipe-selection dialog (REQ-UI-RECIPE-ICON) and belt/port rendering
(REQ-UI-ITEM-ICON). Bold silhouette + dark outline, authored to stay legible
at ~16px belt size: rocky ore chunks, isometric ingots, riveted plates,
copper coil/wire, pictorial module devices, and dart hull silhouettes tinted
per fleet color. No config changes needed — each recipe's icon resolves to
its first output.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Y7N59FsLA5e2kuVdqe4Uhc

bin/app/data/icons/items/voidsteel_plate.svg

@@ -0,0 +1,8 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100" width="100" height="100">
+  <rect x="20" y="28" width="60" height="44" rx="6" fill="#7a5aaa" stroke="#1c1038" stroke-width="4"/>
+  <line x1="26" y1="37" x2="74" y2="37" stroke="#a98fd0" stroke-width="3" stroke-linecap="round"/>
+  <g fill="#180c30">
+    <circle cx="30" cy="39" r="3"/><circle cx="70" cy="39" r="3"/>
+    <circle cx="30" cy="61" r="3"/><circle cx="70" cy="61" r="3"/>
+  </g>
+</svg>