style: tighten playoff card copy — uniform Game X of 7 header, leaner blurbs

Top row now always reads "Game N of 7" (round is already shown by the R1/R2/CONF FINAL/CUP FINAL badge). Bottom blurb drops the trailing period on "Series opener" and uses "{Team} lead X-Y" (plural verb, no "— Game N" suffix) when a leader is established.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tests/test_games.py

@@ -775,7 +775,8 @@ class TestPlayoffEnrichment:
         g = result[0]
         assert g["Is Playoff"] is True
         assert g["Pinned"] is False
-        assert "Game 4" in g["Series Blurb"]
+        assert "lead" in g["Series Blurb"]
+        assert g["Series Summary"] == "Game 4 of 7"
         assert "R1" in g["Series Badges"]
 
     def test_game7_is_pinned(self, mocker):