style: apply ruff format and fix lint issues in playoff modules

- Rename single-letter `l` loop variables in bracket_view to satisfy E741
- Drop unused `json` import from test_playoff_cache (F401/F811)

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

tests/test_routes.py

@@ -188,8 +188,16 @@ class TestSeriesDetailRoute:
                 "startTimeUTC": "2026-04-18T23:00:00Z",
                 "gameState": "OFF",
                 "periodDescriptor": {"number": 3, "periodType": "REG"},
-                "awayTeam": {"abbrev": "OTT", "score": 2, "commonName": {"default": "Senators"}},
-                "homeTeam": {"abbrev": "TOR", "score": 6, "commonName": {"default": "Maple Leafs"}},
+                "awayTeam": {
+                    "abbrev": "OTT",
+                    "score": 2,
+                    "commonName": {"default": "Senators"},
+                },
+                "homeTeam": {
+                    "abbrev": "TOR",
+                    "score": 6,
+                    "commonName": {"default": "Maple Leafs"},
+                },
                 "gameOutcome": {"lastPeriodType": "REG"},
             },
             {
@@ -212,12 +220,14 @@ class TestSeriesDetailRoute:
 
     def test_valid_format_but_missing_cache_404(self, flask_client, monkeypatch):
         import app.routes as routes
+
         monkeypatch.setattr(routes, "fetch_series", lambda sid: None)
         response = flask_client.get("/series/2026-A")
         assert response.status_code == 404
 
     def test_renders_with_cached_payload(self, flask_client, monkeypatch):
         import app.routes as routes
+
         monkeypatch.setattr(routes, "fetch_series", lambda sid: self._SAMPLE_PAYLOAD)
 
         response = flask_client.get("/series/2026-A")
@@ -265,6 +275,7 @@ class TestBracketRoute:
 
     def test_bracket_renders_with_cache(self, flask_client, monkeypatch):
         import app.routes as routes
+
         monkeypatch.setattr(routes, "get_bracket", lambda y: (self._BRACKET, 123))
         monkeypatch.setattr(
             routes,
@@ -283,6 +294,7 @@ class TestBracketRoute:
         self, flask_client, monkeypatch
     ):
         import app.routes as routes
+
         monkeypatch.setattr(routes, "get_bracket", lambda y: (None, None))
         called = {"n": 0}
 
@@ -298,6 +310,7 @@ class TestBracketRoute:
 
     def test_bracket_returns_404_when_no_data(self, flask_client, monkeypatch):
         import app.routes as routes
+
         monkeypatch.setattr(routes, "get_bracket", lambda y: (None, None))
         monkeypatch.setattr(routes, "refresh_bracket", lambda year=None: None)
         response = flask_client.get("/bracket")