Build a single-page widget that converts a pet's age in human years into its equivalent age for common animal species.

The user selects a **pet type** (dog, cat, rabbit, hamster, or parrot) from a small button group, then enters the animal's age in years using a number input. The widget instantly displays the **human-year equivalent** using scientifically-inspired conversion formulas (e.g., dogs: first two years ≈ 10.5 human years each, then ~4 per year after; cats follow a similar curve; smaller animals have much shorter lifespans mapped proportionally).

Below the result, show a fun **life-stage label** — Newborn, Toddler, Teenager, Young Adult, Middle-Aged, Senior, or Elder — based on the translated age. Display a matching emoji or small illustration for each life stage.

The widget should feel polished and delightful: smooth number transitions, a clear species icon next to the selector, and a short flavour sentence like *"Your 3-year-old rabbit is basically a 26-year-old human — peak adulting!"* The entire experience is stateless; no data is saved between sessions.