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>

app/scheduler.py

@@ -14,5 +14,8 @@ def start_scheduler():
     schedule.every(10).seconds.do(refresh_scores)
     logger.info("Background scheduler started")
     while True:
-        schedule.run_pending()
+        try:
+            schedule.run_pending()
+        except Exception:
+            logger.exception("Scheduler encountered an unexpected error")
         time.sleep(1)