roto: video -> take file builder with interactive tuning

Analysis half of the pipeline in docs/roto-puppet.md. Stabilises a face out
of a clip via a similarity fit on rigid landmarks, reduces the lip contour to
a fixed vertex budget, selects sparse keys on velocity minima, and previews
the result as flat indexed fills so timing can be judged without an Animator
Pro render.

- landmarks.js  ordered lip/oval rings; slot position is vertex identity
- mathutil.js   closed-form 2D similarity, Procrustes mean, transform smoothing
- pipeline.js   stabilise -> subsample -> key-select
- raster.js     indexed scanline fill, no antialiasing
- take.js       take-file writer
- selftest.js   29 assertions, incl. ring simplicity at every vertex budget

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

selftest.html

@@ -0,0 +1,20 @@
+<!doctype html>
+<html lang="en"><head><meta charset="utf-8"><title>selftest</title>
+<style>
+ body{background:#0b0d13;color:#e8eaf0;font:13px/1.6 ui-monospace,Menlo,monospace;padding:20px}
+ li{list-style:none} .p{color:#4ade80} .f{color:#f87171}
+ b{font-weight:400;color:#8891a5} h1{font-size:14px}
+</style></head><body>
+<h1 id="head">running…</h1><ul id="out"></ul>
+<script type="module">
+import { run } from './js/selftest.js';
+let res;
+try { res = run(); }
+catch (e) { res = [{ name: 'harness threw: ' + e.message, pass: false, detail: String(e.stack).split('\n')[1] || '' }]; }
+const pass = res.filter(r => r.pass).length;
+const fail = res.length - pass;
+document.getElementById('head').textContent = `${fail === 0 ? 'PASS' : 'FAIL'} — ${pass}/${res.length} assertions`;
+document.title = `${fail === 0 ? 'PASS' : 'FAIL'} ${pass}/${res.length}`;
+document.getElementById('out').innerHTML = res.map(r =>
+  `<li class="${r.pass ? 'p' : 'f'}">${r.pass ? '✓' : '✗'} ${r.name}${r.detail ? ` <b>${r.detail}</b>` : ''}</li>`).join('');
+</script></body></html>