feat: add category and warning filters to Search

[Tubring25]

What does this PR do

Added support for filtering search result by Categories (e.g. F/F, M/M) and Warnings (e.g. Major Character Death)

How to test

You can test the new filters by the following snippet:

import AO3
from AO3.search import CATEGORY_FF, WARNING_VIOLENCE

# Test Category filter
search = AO3.Search(any_field="magic", category_ids=CATEGORY_FF)
search.update()
print(f"Results with FF category: {search.total_results}")

# Test Warning filter
search_warn = AO3.Search(any_field="war", warning_ids=[WARNING_VIOLENCE])
search_warn.update()
print(f"Results with Violence warning: {search_warn.total_results}")

#118