Implement string reversal recursively. Move the first character to the end, reverse the rest.
Your function takes a string and returns it reversed.
Requirements:
- Base case: empty string or single character returns itself
- Recursive case: reverse the substring, append first character at end
- Handle empty strings
Examples:
reverse("hello")->"olleh"reverse("a")->"a"reverse("")->""
The pattern: reverse("abc") = reverse("bc") + "a" = "cb" + "a" = "cba". Each call moves one character to its final position.