Add BDD-style Playwright test suite

[rdhyee]

Summary

• 62 Playwright+pytest tests covering navigation, page content, accordions, Explorer, and data endpoints
• Runs against live site by default, or local preview via ISAMPLES_BASE_URL env var
• ~20 seconds for full suite (non-Explorer tests), ~40 seconds including Explorer

Test files

File	Tests	What it covers
test_navigation.py	21	Sidebar sections match April wireframe, navbar items
test_requirements_page.py	7	18 accordion callouts, collapse/expand behavior
test_key_pages.py	22	Homepage, About, How to Use, Architecture, Publications, data.isamples.org
test_explorer.py	12	Search input, 4 filter categories, facet counts, sample card, view modes

Usage

# All tests against live site
pytest tests/ -p no:base-url

# Against local Quarto preview
ISAMPLES_BASE_URL=http://localhost:5860 pytest tests/ -p no:base-url

Test plan

• 62/62 tests pass against live isamples.org

🤖 Generated with Claude Code