fix(gateway): 对齐号池调度预设行为 (#332)

- 保持 sticky session 优先于分配模式排序，并支持 sticky_session_ttl_seconds=0 禁用粘滞绑定
- 移除旧版 free_team_first 预设入口，统一使用 free_first / team_first 新模式
- 对齐 plus_first 对 Plus/Pro 账号的优先级处理
- 调整负载均衡排序种子，避免同一分钟内固定命中同一 Key
- multi-score 预设下记录延迟样本，并补充号池调度/配置/运行时测试
- 收敛 request candidate extra_data 构造入参，修复 clippy too_many_arguments

apps/aether-gateway/src/handlers/admin/provider/pool/config.rs

@@ -266,7 +266,6 @@ pub(crate) fn admin_provider_pool_config_from_config_value(
         sticky_session_ttl_seconds: pool_advanced
             .get("sticky_session_ttl_seconds")
             .and_then(json_u64)
-            .filter(|value| *value > 0)
             .unwrap_or(3600),
         latency_window_seconds: pool_advanced
             .get("latency_window_seconds")
@@ -389,6 +388,18 @@ mod tests {
         assert_eq!(config.stream_timeout_cooldown_seconds, 180);
     }
 
+    #[test]
+    fn parses_zero_sticky_session_ttl_to_disable_sticky_sessions() {
+        let config = admin_provider_pool_config_from_config_value(Some(&json!({
+            "pool_advanced": {
+                "sticky_session_ttl_seconds": 0
+            }
+        })))
+        .expect("pool config should parse");
+
+        assert_eq!(config.sticky_session_ttl_seconds, 0);
+    }
+
     #[test]
     fn parses_pool_config_from_generic_config_value() {
         let config = admin_provider_pool_config_from_config_value(Some(&json!({