Remove players deleted from Yodeck instead of showing them as offline

Poll loop now deletes DB rows for players no longer returned by the
Yodeck API, and Zabbix sync deletes the corresponding hosts from the
Yodeck Players group. Both actions are reflected in the activity log.

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

app/database.py

@@ -115,6 +115,18 @@ def upsert_player(p):
     conn.close()
 
 
+def delete_players_not_in(ids):
+    if not ids:
+        return 0
+    placeholders = ','.join('?' * len(ids))
+    conn = _conn()
+    cur = conn.execute(f'DELETE FROM players WHERE id NOT IN ({placeholders})', ids)
+    deleted = cur.rowcount
+    conn.commit()
+    conn.close()
+    return deleted
+
+
 def get_all_players():
     conn = _conn()
     rows = conn.execute('SELECT * FROM players ORDER BY name').fetchall()