feat: add transfers crawler

[cesarpmorais]

Transfers Crawler

This PR adds a transfers crawler that scrapes player arrivals and departures from Transfermarkt club and competition transfer pages.

About #89 — the original approach proposed using Scrapy, which was lateconsidered overkill for this use case by the maintainer. This implementation uses Crawlee instead, matching the framework adopted by the project in #97.

Usage

# scrape transfers for a competition
echo '{"href":"/premier-league/transfers/wettbewerb/GB1/plus/?saison_id=2025&s_w=&leihe=1&intern=0&intern=1"}' \
    | python -m tfmkt transfers > transfers.json

# scrape transfers for a single club
echo '{"href":"/ec-cruzeiro-belo-horizonte/transfers/verein/609/saison_id/2025"}' \
    | python -m tfmkt transfers > transfers.json

# chain with the clubs crawler
cat competitions.json | head -1 \
    | python -m tfmkt clubs \
    | python -m tfmkt transfers > transfers.json

[dcaribou]

Hey @cesarpmorais, thanks for your PR!

One question. What'd be the advantage of scraping this data from the html vs querying the public transfers API like here for example?