Build initial logic skeleton benchmark

tasks/short-smoke.json

@@ -0,0 +1,8 @@
+{
+  "name": "short-smoke",
+  "description": "Render and solve one short example from each initial skeleton family.",
+  "count": 3,
+  "length": "short",
+  "seed": 20260922,
+  "output_dir": "artifacts/short-smoke"
+}