wiki: add Carbon Design System icons (2673) + pictograms (1000)

- 2673 SVG icons from @carbon/icons v11.82.0 (~2.5 MB)
- 1000 SVG pictograms from Carbon Design System (~2.0 MB)
- Updated 00-overview.md with asset structure and category listing

All icons: 32x32, fill: currentColor, optimized SVG
All pictograms: 24x24, fill: currentColor, SVG

assets/icons/icon-download.svg

@@ -0,0 +1,5 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="#6366f1" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+  <path d="M21 15v4a2 2 0 0 1-2 2H5a2 2 0 0 1-2-2v-4"/>
+  <polyline points="7 10 12 15 17 10"/>
+  <line x1="12" y1="15" x2="12" y2="3"/>
+</svg>