feat: add ponytail skill, examples, README

examples/email-validation.md

@@ -0,0 +1,51 @@
+# Email Validation
+
+**Task:** "Validate an email address in Python."
+
+## Without Ponytail
+
+```python
+import re
+
+EMAIL_PATTERN = re.compile(
+    r'^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$'
+)
+
+class EmailValidator:
+    """Validates email addresses against RFC-like rules."""
+
+    def __init__(self, pattern: re.Pattern = EMAIL_PATTERN):
+        self.pattern = pattern
+
+    def validate(self, email: str) -> bool:
+        if not isinstance(email, str):
+            raise TypeError("email must be a string")
+        email = email.strip()
+        if not email:
+            return False
+        return bool(self.pattern.match(email))
+
+
+def validate_email(email: str) -> bool:
+    """Convenience wrapper around EmailValidator."""
+    return EmailValidator().validate(email)
+```
+
+A class, a wrapper, a regex that still rejects valid addresses and accepts invalid ones. Regex cannot validate email. Only a delivery attempt can.
+
+## With Ponytail
+
+```python
+# ponytail: good enough — real validation is sending the mail
+"@" in email and "." in email.split("@")[-1]
+```
+
+Or, if it must be thorough, the standard library has it:
+
+```python
+# ponytail: stdlib covers this
+from email.utils import parseaddr
+"@" in parseaddr(email)[1]
+```
+
+**27 lines → 1 line.** And the honest answer: let the confirmation email reject it. That's what confirmation emails are for.