fix: resolve 4 logic bugs found in code review

- utc_to_eastern: use zoneinfo instead of hardcoded EDT offset (-4)
  so start times are correct in both EST and EDT
- standings: fetch before truncate so a failed API call doesn't wipe
  existing standings data
- routes: call parse_games() once per request instead of three times
- scheduler: wrap run_pending() in try/except so an unhandled exception
  doesn't kill the background thread

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/test_scheduler.py

@@ -39,3 +39,20 @@ class TestStartScheduler:
             start_scheduler()
 
         assert mock_schedule.run_pending.call_count >= 2
+
+    def test_continues_after_exception_in_run_pending(self, mocker):
+        mock_schedule = mocker.patch("app.scheduler.schedule")
+        call_count = {"n": 0}
+
+        def raise_then_stop(_):
+            call_count["n"] += 1
+            if call_count["n"] >= 2:
+                raise StopIteration
+
+        mock_schedule.run_pending.side_effect = RuntimeError("boom")
+        mocker.patch("app.scheduler.time.sleep", side_effect=raise_then_stop)
+
+        with pytest.raises(StopIteration):
+            start_scheduler()
+
+        assert mock_schedule.run_pending.call_count >= 2