Typing Effect

Create a React + TypeScript hook + component pair: `useTypewriter` and `TypingText`, implementing a genuinely working typewriter that types, pauses, deletes and cycles through an array of words with a blinking caret.

`useTypewriter(words: string[], opts?)` must:
- Accept `typeSpeed = 70`, `deleteSpeed = 40`, `pauseMs = 1600`, `loop = true`.
- Keep state `{ text, wordIndex, isDeleting }` and drive it with a single `useEffect` + `setTimeout` scheduled from the current phase; ALWAYS clear the timeout in the cleanup to avoid double-speed typing in React 18 StrictMode.
- When the word is fully typed, wait `pauseMs`, then delete; when empty, move to `(wordIndex + 1) % words.length`.
- Return `{ text, isDeleting }`.