Move SVG diagrams to separate files for GitHub rendering

Inline SVGs are stripped by GitHub's markdown sanitizer. Moved all 11
diagrams to docs/diagrams/*.svg and referenced them with <img> tags.

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

docs/diagrams/video-inpaint.svg

@@ -0,0 +1,20 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 600 90" style="max-width:600px">
+  <text y="12" font-size="11" font-family="sans-serif" fill="#888">mask (per-pixel)</text>
+  <defs>
+    <pattern id="checker" width="16" height="16" patternUnits="userSpaceOnUse">
+      <rect width="8" height="8" fill="#222"/>
+      <rect x="8" width="8" height="8" fill="#fff"/>
+      <rect y="8" width="8" height="8" fill="#fff"/>
+      <rect x="8" y="8" width="8" height="8" fill="#222"/>
+    </pattern>
+  </defs>
+  <rect x="0" y="18" width="600" height="28" rx="4" fill="url(#checker)"/>
+  <rect x="0" y="18" width="600" height="28" rx="4" fill="rgba(0,0,0,0.4)"/>
+  <text x="300" y="36" text-anchor="middle" font-size="12" font-family="sans-serif" fill="#fff">per-pixel mask broadcast to (B, H, W, 3)</text>
+  <text y="62" font-size="11" font-family="sans-serif" fill="#888">control_frames (per-pixel composite)</text>
+  <rect x="0" y="68" width="300" height="28" rx="4" fill="#4a9ebb"/>
+  <rect x="300" y="68" width="300" height="28" rx="4" fill="#999"/>
+  <text x="150" y="86" text-anchor="middle" font-size="11" font-family="sans-serif" fill="#fff">source pixels (mask=0)</text>
+  <text x="450" y="86" text-anchor="middle" font-size="11" font-family="sans-serif" fill="#fff">grey pixels (mask=1)</text>
+  <text x="300" y="82" text-anchor="middle" font-size="9" font-family="sans-serif" fill="#ddd">↕ blended per-pixel</text>
+</svg>