feat: add repo-tokens GitHub Action with token count badge

Reusable composite action that counts codebase tokens using tiktoken
and generates a shields.io-style SVG badge. Color reflects context
window usage: green (<30%), yellow-green (30-50%), yellow (50-70%),
red (70%+). Badge includes hardcoded link back to repo-tokens.

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

repo-tokens/badge.svg

@@ -0,0 +1,23 @@
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="97" height="20" role="img" aria-label="34.9k tokens, 17% of context window">
+  <title>34.9k tokens, 17% of context window</title>
+  <linearGradient id="s" x2="0" y2="100%">
+    <stop offset="0" stop-color="#bbb" stop-opacity=".1"/>
+    <stop offset="1" stop-opacity=".1"/>
+  </linearGradient>
+  <clipPath id="r">
+    <rect width="97" height="20" rx="3" fill="#fff"/>
+  </clipPath>
+  <a xlink:href="https://github.com/qwibitai/nanoclaw/tree/main/repo-tokens">
+    <g clip-path="url(#r)">
+      <rect width="52" height="20" fill="#555"/>
+      <rect x="52" width="45" height="20" fill="#4c1"/>
+      <rect width="97" height="20" fill="url(#s)"/>
+      <g fill="#fff" text-anchor="middle" font-family="Verdana,Geneva,DejaVu Sans,sans-serif" font-size="11">
+        <text aria-hidden="true" x="26" y="15" fill="#010101" fill-opacity=".3">tokens</text>
+        <text x="26" y="14">tokens</text>
+        <text aria-hidden="true" x="74" y="15" fill="#010101" fill-opacity=".3">34.9k</text>
+        <text x="74" y="14">34.9k</text>
+      </g>
+    </g>
+  </a>
+</svg>