add bet impact simulator, visitor log page, and fix console logging

- Bet impact simulator on /predictions shows rank headroom and safe bet amounts
- Password-protected /visitors page with visitor log table and stats
- Console now logs real visitor IPs instead of Cloudflare tunnel IPs

app/db.py

@@ -177,6 +177,30 @@ def insert_visitors(batch: list[dict]):
     )
 
 
+@_with_lock
+def get_recent_visitors(limit: int = 200) -> list[dict]:
+    """Get recent visitor log entries."""
+    client = get_client()
+    result = client.query(
+        "SELECT ip, country, path, method, user_agent, referer, accept_lang, created_at "
+        "FROM visitors ORDER BY created_at DESC LIMIT {limit:UInt32}",
+        parameters={"limit": limit},
+    )
+    visitors = []
+    for row in result.result_rows:
+        visitors.append({
+            "ip": row[0],
+            "country": row[1],
+            "path": row[2],
+            "method": row[3],
+            "user_agent": row[4],
+            "referer": row[5],
+            "accept_lang": row[6],
+            "created_at": str(row[7]),
+        })
+    return visitors
+
+
 @_with_lock
 def get_recent_games(n: int = 50) -> list[dict]:
     """Get last N completed games."""