feat: add categorized dork dictionaries

[techgaun]

Summary

• split all 127 active dorks into seven focused category files
• add cloud, databases, devops, frameworks, private-keys, saas, and system dictionaries
• add repeatable -c/--category selection
• add --list-categories without constructing a GitHub client
• allow category selection in monitoring mode
• retain custom -d/--dork files and make them mutually exclusive with bundled categories
• retain github-dorks.txt as the default backward-compatible aggregate
• generate the aggregate deterministically with scripts/build-dorks.py
• package category files as wheel resources
• document category discovery and selection

Compatibility

With no --category or custom --dork, scans continue using github-dorks.txt and run the same 127 queries as before. The split is lossless: category union and aggregate contain identical unique dorks.

Verification

• python3 -m unittest discover -s tests -v (28 tests)
• aggregate regeneration equality test
• aggregate/category set and count equality test
• no duplicates across categories
• flflake8 in Python 3.12
• git diff --check
• Docker image/package build
• wheel-installed --list-categories from /tmp