Word Search: pin per-size counts in test + fix stale .playing-word comment

Per Codex audit. test_wordsearch_endpoint now asserts the exact promise — small 6,
med 9, large 13, pairwise-disjoint. app.css comment updated to .playing-game (the
class was renamed when the focused viewport was generalized to both games).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/test_admin.py

@@ -334,7 +334,9 @@ def test_wordsearch_endpoint(tmp_path, monkeypatch):
         assert all(findable(r["grid"], dim, w) for w in r["words"])  # every word placed → solvable
         themes.add(r["theme"]); per_size[tier] = set(r["words"])
     assert len(themes) == 1  # all sizes share the day's one theme
-    # the three sizes are DISJOINT — each day is three distinct puzzles
+    # frozen promise: exact per-size counts ...
+    assert len(per_size["small"]) == 6 and len(per_size["med"]) == 9 and len(per_size["large"]) == 13
+    # ... and the three sizes are DISJOINT — each day is three distinct puzzles
     assert per_size["small"] & per_size["med"] == set()
     assert per_size["small"] & per_size["large"] == set()
     assert per_size["med"] & per_size["large"] == set()