Address CodeRabbit review: font-name traversal + offline test guard

Two Minor findings from CodeRabbit's first review of this PR.

- resolve_font_path: reject relative font names carrying path components.
  font_name comes from plugin config, which the web UI writes; a value like
  "../../config/config.json" escaped assets/fonts/ after os.path.join and let
  a config probe arbitrary paths for existence (disclosure unlikely, since
  Pillow/freetype reject non-font files, but the probe is real). Relative
  names must now be bare filenames (os.path.basename(name) == name); absolute
  paths keep their existing isfile() gate. Test confirms the traversal
  resolved the real config.json before the guard.

- build_manager fixture: patch requests.Session.get BEFORE constructing the
  manager. Construction creates both SportsCore.session and the
  ESPNDataSource.session; the old code only replaced manager.session after
  the fact, leaving data_source.session real and able to reach the network on
  an accidental fetch. Patching the class makes every session built in the
  fixture offline.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KEZK1P1Q1fu5pcuVrkrCFZ

test/test_element_style.py

@@ -377,6 +377,22 @@ class TestResolverPlumbing:
         font = load_font("5x7.bdf", 7)
         assert isinstance(font, freetype.Face)
 
+    @pytest.mark.parametrize("hostile", [
+        "../../config/config.json",
+        "../secrets.txt",
+        "sub/dir/font.ttf",
+        "..",
+    ])
+    def test_relative_font_name_with_path_components_is_rejected(self, hostile):
+        # font_name comes from plugin config (web-UI writable); a relative name
+        # carrying path separators would escape assets/fonts/ after os.path.join
+        # and let a config probe arbitrary paths. Only bare filenames resolve.
+        assert resolve_font_path(hostile) is None
+
+    def test_bare_filename_still_resolves(self):
+        # The guard must not reject legitimate bare names.
+        assert resolve_font_path("PressStart2P-Regular.ttf") is not None
+
     def test_schema_manager_expands_on_load(self, tmp_path):
         # The web-UI form path: SchemaManager.load_schema serves the
         # expanded schema so the style blocks actually appear in the UI.

test/test_sports_base_characterization.py

@@ -403,6 +403,17 @@ def build_manager(monkeypatch, tmp_path):
         "src.base_classes.sports.get_background_service",
         lambda *args, **kwargs: MagicMock())
 
+    # Rig requests.Session BEFORE any manager is built. Construction creates
+    # both SportsCore.session and the ESPNDataSource.session; replacing only
+    # manager.session after the fact (below) leaves data_source.session real,
+    # so an accidental fetch during or right after construction could reach
+    # the network. Patching the class makes every session created here raise.
+    def _offline_get(*args, **kwargs):
+        raise requests.exceptions.ConnectionError(
+            "characterization tests are offline")
+
+    monkeypatch.setattr(requests.Session, "get", _offline_get)
+
     def build(cls, schedule, **mode_cfg):
         config = {
             "timezone": "UTC",