Add effects count to home page dashboard

- Add Effects card to home page grid (now 3 columns)
- Add stats["effects"] count from cache.list_by_type('effect')
- Add tests for home page effects display

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

tests/test_effects_web.py

@@ -235,6 +235,28 @@ def process_frame(frame, params, state):
         assert "multi-line" in meta["description"]
 
 
+class TestHomePageEffectsCount:
+    """Test that effects count is shown on home page."""
+
+    def test_home_template_has_effects_card(self) -> None:
+        """Home page should display effects count."""
+        path = Path('/home/giles/art/art-celery/app/templates/home.html')
+        content = path.read_text()
+
+        assert 'stats.effects' in content, \
+            "Home page should display stats.effects count"
+        assert 'href="/effects"' in content, \
+            "Home page should link to /effects"
+
+    def test_home_route_provides_effects_count(self) -> None:
+        """Home route should provide effects count in stats."""
+        path = Path('/home/giles/art/art-celery/app/routers/home.py')
+        content = path.read_text()
+
+        assert 'stats["effects"]' in content, \
+            "Home route should populate stats['effects']"
+
+
 class TestNavigationIncludesEffects:
     """Test that Effects link is in navigation."""