skip visual tests in CI — require explicit -m visual flag

Playwright visual tests need browser binaries (playwright install
chromium) which CI doesn't have. Mark them with pytest.mark.visual
and add addopts = "-m 'not visual'" so they're skipped by default.

Run locally with: uv run pytest -m visual tests/test_visual.py -v

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

padelnomics/pyproject.toml

@@ -43,3 +43,5 @@ ignore = ["E501"]
 [tool.pytest.ini_options]
 asyncio_mode = "auto"
 testpaths = ["tests"]
+markers = ["visual: Playwright visual tests (require browser install)"]
+addopts = "-m 'not visual'"

padelnomics/tests/test_visual.py

@@ -4,8 +4,9 @@ Visual regression tests using Playwright.
 Takes screenshots of key pages and verifies styling invariants
 (heading colors, backgrounds, nav layout, logo presence).
 
-Usage:
-    uv run pytest tests/test_visual.py -x -v
+Skipped by default (requires `playwright install chromium`).
+Run explicitly with:
+    uv run pytest -m visual tests/test_visual.py -v
 
 Screenshots are saved to tests/screenshots/ for manual review.
 """
@@ -21,6 +22,8 @@ from playwright.sync_api import expect, sync_playwright
 from padelnomics import core
 from padelnomics.app import create_app
 
+pytestmark = pytest.mark.visual
+
 SCREENSHOTS_DIR = Path(__file__).parent / "screenshots"
 SCREENSHOTS_DIR.mkdir(exist_ok=True)