feat: add PDF Keyword Highlighter script (closes #478)

[SurfyPenguin]

PR Title

feat: add PDF Keyword Highlighter script (closes #478 )

Summary

Added a new command-line Python script that highlights specified keywords in PDF files using PyMuPDF, complete with a dedicated folder, README, and entry in the main repository README.

Description

This pull request implements a fully featured PDF keyword highlighter as requested in issue #478, creating a new highlighted output file while keeping the original unchanged.

The changes are as follows:

• Created new folder PDF Highlighter Script/ with pdf_highlight.py and a README.md
• Implemented efficient keyword highlighting using page.get_text("words") for fast text extraction
• Supported multiple keywords, optional case-sensitive search (-s flag), and punctuation stripping for accurate matching (e.g., "keyword;" matches "keyword")
• Printed per-page and total highlight statistics in a formatted table
• Updated root README.md to add the new script entry in alphabetical order

Checks

in the repository

• Made no changes that degrades the functioning of the repository
• Gave each commit a better title (unlike updated README.md)

in the PR

• Followed the format of the pull_request_template
• Made the Pull Request in a small level (for the creator's wellfare)
• Tested the changes you made

Thank You,

Amartya Anand