feat: add separator prop to TrueFocus component for customizable word separation

[KavanBhavsar35]

Summary

Fixes #676
This PR refines the TrueFocus component by replacing the previously proposed words prop idea with an optional separator parameter.
The new separator prop (default: " ") lets developers control how the sentence string is split into words, enabling flexible customization of text segmentation.

---

Changes

• Added optional prop:

  separator?: string // default: " "

• Words are now derived via sentence.split(separator) instead of being fixed to spaces.

• Removed the previously proposed words prop (discarded).

• Updated logic and typings to reflect this behavior.

• Maintains full backward compatibility — existing usage remains unchanged.

---

Motivation

Previously, words were always split by a single space, which limited flexibility for custom delimiters or multi-word tokens.
The new separator option allows developers to use any string as a delimiter, such as:

<TrueFocus sentence="One|Two|Three" separator="|" />

[DavidHDev]

Great! Thanks!