Add detailed README with SVG diagrams and Apache 2.0 license

Includes algorithm comparison, node wiring, and parameter guide
diagrams. SVGs use <picture> tags for GitHub compatibility.

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

assets/banner.svg

@@ -0,0 +1,18 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 900 200">
+  <defs>
+    <linearGradient id="bg" x1="0%" y1="0%" x2="100%" y2="100%">
+      <stop offset="0%" style="stop-color:#1a1a2e"/>
+      <stop offset="50%" style="stop-color:#16213e"/>
+      <stop offset="100%" style="stop-color:#0f3460"/>
+    </linearGradient>
+    <linearGradient id="accent" x1="0%" y1="0%" x2="100%" y2="0%">
+      <stop offset="0%" style="stop-color:#e94560"/>
+      <stop offset="100%" style="stop-color:#533483"/>
+    </linearGradient>
+  </defs>
+  <rect width="900" height="200" rx="12" fill="url(#bg)"/>
+  <rect x="0" y="185" width="900" height="15" rx="0 0 12 12" fill="url(#accent)" opacity="0.8"/>
+  <text x="450" y="75" font-family="Segoe UI, Helvetica, Arial, sans-serif" font-size="48" font-weight="700" fill="#ffffff" text-anchor="middle">SMC-CFG Ctrl</text>
+  <text x="450" y="115" font-family="Segoe UI, Helvetica, Arial, sans-serif" font-size="20" fill="#a0a0c0" text-anchor="middle">Sliding Mode Control for Classifier-Free Guidance</text>
+  <text x="450" y="150" font-family="Segoe UI, Helvetica, Arial, sans-serif" font-size="15" fill="#707090" text-anchor="middle">ComfyUI Node  |  Based on CFG-Ctrl (CVPR 2026)</text>
+</svg>