[Good First Issue] Add pytest CI — run tests on every push and PR

[kamsirichard]

Context

@saurabhhhcodes added test files in PRs #37, #38, and #39 — there are now real tests in tests/. They never run automatically. This issue is to wire them up.

Task

Create .github/workflows/tests.yml that:

1. Triggers on push and pull_request (all branches)
2. Sets up Python 3.11
3. Runs pip install -r requirements.txt
4. Runs pytest tests/ -v

Expected result

Every PR shows a green/red test badge before it gets reviewed. No more merging broken code accidentally.

Notes

• The existing test files live in tests/ (created by @saurabhhhcodes)
• Tests stub out Scrapy so they run without a live spider
• This is a single YAML file — no Python changes needed

Good for

Anyone comfortable with GitHub Actions YAML. Estimated time: 30–60 minutes.