feat: add ponytail skill, examples, README

examples/date-picker.md

@@ -0,0 +1,48 @@
+# Date Picker
+
+**Task:** "Add a date picker to this form."
+
+## Without Ponytail
+
+```bash
+npm install flatpickr
+```
+
+```jsx
+import flatpickr from "flatpickr";
+import "flatpickr/dist/flatpickr.min.css";
+import { useEffect, useRef } from "react";
+
+export default function DatePicker({ value, onChange, minDate, maxDate }) {
+  const inputRef = useRef(null);
+  const instanceRef = useRef(null);
+
+  useEffect(() => {
+    instanceRef.current = flatpickr(inputRef.current, {
+      defaultDate: value,
+      minDate,
+      maxDate,
+      dateFormat: "Y-m-d",
+      onChange: ([date]) => onChange(date),
+    });
+    return () => instanceRef.current?.destroy();
+  }, []);
+
+  useEffect(() => {
+    instanceRef.current?.setDate(value, false);
+  }, [value]);
+
+  return <input ref={inputRef} className="date-picker" />;
+}
+```
+
+One dependency, one wrapper component, two `useEffect` hooks, a cleanup function, and a CSS import — to pick a date.
+
+## With Ponytail
+
+```html
+<!-- ponytail: browser has one -->
+<input type="date">
+```
+
+**1 dependency + 30 lines → 0 dependencies + 1 line.** Native, accessible, localized, keyboard-navigable, mobile-friendly. The browser team already did the work.