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/routes.py

@@ -25,24 +25,12 @@ def get_scoreboard():
         )
 
     if scoreboard_data:
-        live_games = [
-            game
-            for game in parse_games(scoreboard_data)
-            if game["Game State"] == "LIVE"
-        ]
-        pre_games = [
-            game for game in parse_games(scoreboard_data) if game["Game State"] == "PRE"
-        ]
-        final_games = [
-            game
-            for game in parse_games(scoreboard_data)
-            if game["Game State"] == "FINAL"
-        ]
+        games = parse_games(scoreboard_data)
         return jsonify(
             {
-                "live_games": live_games,
-                "pre_games": pre_games,
-                "final_games": final_games,
+                "live_games": [g for g in games if g["Game State"] == "LIVE"],
+                "pre_games": [g for g in games if g["Game State"] == "PRE"],
+                "final_games": [g for g in games if g["Game State"] == "FINAL"],
             }
         )
     else: