feat: add category support to JSON outputs (#267)

[Ruhi14]

This PR adds category metadata to the blns.json and blns.base64.json outputs based on the section headers from blns.txt.

✅ Changes:

• Added scripts/generate_json_with_categories.py for converting categorized .txt to .json
• Replaced blns.json and blns.base64.json with structured objects
• Each JSON entry now includes a "category" field (and base64 if applicable)

Fixes #267

[QuLogic]

Instead of repeating the category every time, why not do something like [{"category": "The category.", "strings": ["1", "2, "3", ...]}, ...]