docs(design): add logo assets + wordmark pattern

Copies logo files from the product UI into public/ so the website
instance has the real assets from day one:

- public/logo.svg — 32×32 SVG icon (slate-950 bg + sky-400 network motif),
  sourced from ui/public/favicon.svg; used for nav, favicon, inline marks
- public/logo.png — 1024×1024 RGBA PNG; used for OG image and large displays

docs/DESIGN.md gains a "Logo Assets" section with:
- file table (format, size, intended use)
- inline SVG snippet ready to paste into React components
- wordmark pattern (net + Ork in sky-400) that ties logo to accent color
- <head> reference snippets for favicon and OG image

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

public/logo.svg

@@ -0,0 +1,12 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 32" fill="none">
+  <circle cx="16" cy="16" r="16" fill="#0f172a"/>
+  <circle cx="16" cy="16" r="5" fill="#38bdf8"/>
+  <circle cx="8"  cy="8"  r="3" fill="#38bdf8" opacity=".7"/>
+  <circle cx="24" cy="8"  r="3" fill="#38bdf8" opacity=".7"/>
+  <circle cx="8"  cy="24" r="3" fill="#38bdf8" opacity=".7"/>
+  <circle cx="24" cy="24" r="3" fill="#38bdf8" opacity=".7"/>
+  <line x1="11" y1="11" x2="16" y2="16" stroke="#38bdf8" stroke-width="1.5" opacity=".5"/>
+  <line x1="21" y1="11" x2="16" y2="16" stroke="#38bdf8" stroke-width="1.5" opacity=".5"/>
+  <line x1="11" y1="21" x2="16" y2="16" stroke="#38bdf8" stroke-width="1.5" opacity=".5"/>
+  <line x1="21" y1="21" x2="16" y2="16" stroke="#38bdf8" stroke-width="1.5" opacity=".5"/>
+</svg>