Fix analysis dashboard trend data field mapping

- Update web.py to use flagged_posts/flagged_mentions fields
- Matches data structure returned by analysis_helpers

Analysis dashboard and trend graph now working correctly

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app/web.py

@@ -455,7 +455,8 @@ def analysis_dashboard():
             {
                 "week": r["week"].strftime("%Y-%m-%d") if r["week"] else "",
                 "avg_toxicity": round(float(r["avg_toxicity"]), 4),
-                "flagged_statuses": int(r["flagged_statuses"]),
+                "flagged_posts": int(r["flagged_posts"]),
+                "flagged_mentions": int(r["flagged_mentions"]),
             }
             for r in trend
         ])