feat(gateway): 重构 usage 数据层、迁移系统与系统导入

数据库迁移:
- 引入 baseline v2 bootstrap，空库首次启动自动初始化
- 服务启动不再自动执行迁移，需显式 `--migrate` 运行
- 新增 pending migration 检测，schema 落后时拒绝启动

Usage 数据层:
- usage body 存储外部化为独立 blob 表
- 新增 HTTP audit 表拆分存储请求/响应头与 body ref
- 后台清理任务支持 legacy body ref 元数据迁移
- usage runtime 写入迁移到专用 tokio runtime（独立线程池, 8MB 栈）

系统导入/导出:
- 支持用户、API Keys、钱包数据的完整导入
- 兼容 legacy 与 v1.3+ 两种导出格式

其他改进:
- executor outcome 增加 runtime miss 诊断上下文
- 主 tokio runtime 栈大小调整为 8MB
- 前端 provider 管理支持 base URL 配置
- dev.sh 支持 --migrate 参数

apps/aether-gateway/src/state/core.rs

@@ -252,6 +252,28 @@ impl AppState {
         Ok(true)
     }
 
+    pub async fn pending_postgres_migrations(
+        &self,
+    ) -> Result<Option<Vec<aether_data::migrate::PendingMigrationInfo>>, sqlx::migrate::MigrateError>
+    {
+        let Some(pool) = self.postgres_pool() else {
+            return Ok(None);
+        };
+        Ok(Some(aether_data::migrate::pending_migrations(&pool).await?))
+    }
+
+    pub async fn prepare_postgres_for_startup(
+        &self,
+    ) -> Result<Option<Vec<aether_data::migrate::PendingMigrationInfo>>, sqlx::migrate::MigrateError>
+    {
+        let Some(pool) = self.postgres_pool() else {
+            return Ok(None);
+        };
+        Ok(Some(
+            aether_data::migrate::prepare_database_for_startup(&pool).await?,
+        ))
+    }
+
     pub fn with_video_task_poller_config(mut self, interval: Duration, batch_size: usize) -> Self {
         self.video_task_poller = Some(VideoTaskPollerConfig {
             interval,
@@ -559,10 +581,17 @@ impl AppState {
         trace_id: &str,
         diagnostic: LocalExecutionRuntimeMissDiagnostic,
     ) {
-        self.local_execution_runtime_miss_diagnostics
+        let mut diagnostics = self
+            .local_execution_runtime_miss_diagnostics
             .lock()
-            .expect("local execution runtime miss diagnostics should lock")
-            .insert(trace_id.to_string(), diagnostic);
+            .expect("local execution runtime miss diagnostics should lock");
+        if diagnostics
+            .get(trace_id)
+            .is_some_and(|existing| should_preserve_runtime_miss_diagnostic(existing, &diagnostic))
+        {
+            return;
+        }
+        diagnostics.insert(trace_id.to_string(), diagnostic);
     }
 
     pub(crate) fn mutate_local_execution_runtime_miss_diagnostic<F>(
@@ -581,6 +610,17 @@ impl AppState {
         }
     }
 
+    pub(crate) fn local_execution_runtime_miss_diagnostic_has_candidate_signal(
+        &self,
+        trace_id: &str,
+    ) -> bool {
+        self.local_execution_runtime_miss_diagnostics
+            .lock()
+            .expect("local execution runtime miss diagnostics should lock")
+            .get(trace_id)
+            .is_some_and(runtime_miss_diagnostic_has_candidate_signal)
+    }
+
     pub(crate) fn take_local_execution_runtime_miss_diagnostic(
         &self,
         trace_id: &str,
@@ -735,3 +775,19 @@ impl AppState {
         tasks
     }
 }
+
+fn should_preserve_runtime_miss_diagnostic(
+    existing: &LocalExecutionRuntimeMissDiagnostic,
+    next: &LocalExecutionRuntimeMissDiagnostic,
+) -> bool {
+    runtime_miss_diagnostic_has_candidate_signal(existing)
+        && !runtime_miss_diagnostic_has_candidate_signal(next)
+}
+
+fn runtime_miss_diagnostic_has_candidate_signal(
+    diagnostic: &LocalExecutionRuntimeMissDiagnostic,
+) -> bool {
+    diagnostic.candidate_count.unwrap_or(0) > 0
+        || diagnostic.skipped_candidate_count.unwrap_or(0) > 0
+        || !diagnostic.skip_reasons.is_empty()
+}