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_playoff_series.py

@@ -69,7 +69,7 @@ class TestSeriesState:
 class TestSeriesBlurb:
     def test_opener_blurb(self):
         game = make_playoff_game(top_wins=0, bottom_wins=0)
-        assert series_blurb(game) == "Series opener."
+        assert series_blurb(game) == "Series opener"
 
     def test_game7_blurb(self):
         game = make_playoff_game(top_wins=3, bottom_wins=3)
@@ -96,8 +96,8 @@ class TestSeriesBlurb:
     def test_leader_trailer_blurb(self):
         game = make_playoff_game(top_wins=2, bottom_wins=1)
         blurb = series_blurb(game)
-        assert "leads" in blurb
-        assert "Game 4" in blurb
+        assert "lead" in blurb
+        assert "2\u20111" in blurb
 
     def test_tied_mid_series_blurb(self):
         game = make_playoff_game(top_wins=1, bottom_wins=1)
@@ -139,15 +139,15 @@ class TestSeriesBadges:
 class TestSeriesSummary:
     def test_opener_summary(self):
         game = make_playoff_game(top_wins=0, bottom_wins=0, round_num=1)
-        assert "Round 1" in series_summary(game)
+        assert series_summary(game) == "Game 1 of 7"
 
     def test_leader_summary(self):
         game = make_playoff_game(top_wins=2, bottom_wins=1)
-        assert "leads" in series_summary(game)
+        assert series_summary(game) == "Game 4 of 7"
 
     def test_tied_mid_series_summary(self):
         game = make_playoff_game(top_wins=1, bottom_wins=1)
-        assert "tied" in series_summary(game).lower()
+        assert series_summary(game) == "Game 3 of 7"
 
 
 class TestIsPinned: