fix(build): 修复网关构建失败并收口候选选择与 finalize 回归

- 补齐 DecisionTraceCandidate 新增字段，修复审计测试构造
- 修正 usage 内存仓库的 created_at_unix_ms 字段引用与秒/毫秒换算
- 将 build_minimal_candidate_selection 重构为输入对象，消除 clippy 参数过多问题
- 修复 admin global model created_at 旧字段残留引用
- 修复 openai:cli 与 openai:compact 同家族 finalize 在 needs_conversion=true 时的成功回落逻辑
- 清理 aether-gateway 中的 derive/default 与 needless borrow 等 clippy 问题

apps/aether-gateway/src/scheduler/config.rs

@@ -2,19 +2,14 @@ use aether_scheduler_core::SchedulerPriorityMode;
 
 use crate::{AppState, GatewayError};
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
 pub(crate) enum SchedulerSchedulingMode {
     FixedOrder,
+    #[default]
     CacheAffinity,
     LoadBalance,
 }
 
-impl Default for SchedulerSchedulingMode {
-    fn default() -> Self {
-        Self::CacheAffinity
-    }
-}
-
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub(crate) struct SchedulerOrderingConfig {
     pub(crate) priority_mode: SchedulerPriorityMode,