feat(stats,rules): api_key 用量统计（total_tokens 字段 + 回填）与 body rules 新增 append/insert/regex_replace/name_style 操作

- 新增迁移 20260422120000_add_api_key_usage_stats.sql，为 api_keys 表添加 total_tokens 列
- 新增回填 20260422120000_backfill_api_key_usage_stats.sql，按历史 usage 重建 api_key 维度汇总
- 在 UsageWriteRepository trait 中添加 rebuild_api_key_usage_stats，补齐 SQL/内存实现及上层调用链
- 内存实现中新增 apply_usage_stats_delta，支持增量更新 api_key 统计快照
- dev.sh：改进临时日志目录管理，并在网关异常退出时输出错误提示
- frontend EndpointFormDialog：将 append 操作从 insert 分支拆分，提供独立 path/value 输入 UI
- rules.rs：扩展 body rules 支持，新增 append/insert/regex_replace/name_style 操作及 WildcardSlice 路径段

crates/aether-data/src/repository/auth/memory.rs

@@ -9,6 +9,7 @@ use super::types::{
     StandaloneApiKeyExportListQuery, StoredAuthApiKeyExportRecord, StoredAuthApiKeySnapshot,
     UpdateStandaloneApiKeyBasicRecord, UpdateUserApiKeyBasicRecord,
 };
+use crate::repository::usage::{ApiKeyUsageContribution, ApiKeyUsageDelta};
 use crate::DataLayerError;
 
 #[derive(Debug, Default)]
@@ -111,6 +112,70 @@ impl InMemoryAuthApiKeySnapshotRepository {
             .copied()
             .unwrap_or(0)
     }
+
+    pub(crate) fn apply_usage_stats_delta(
+        &self,
+        api_key_id: &str,
+        delta: &ApiKeyUsageDelta,
+        _recomputed_last_used_at_unix_secs: Option<u64>,
+    ) {
+        let mut index = self
+            .index
+            .write()
+            .expect("auth api key snapshot repository lock");
+        let Some(record) = index.export_by_api_key_id.get_mut(api_key_id) else {
+            return;
+        };
+
+        record.total_requests = apply_i64_delta_to_u64(record.total_requests, delta.total_requests);
+        record.total_tokens = apply_i64_delta_to_u64(record.total_tokens, delta.total_tokens);
+        record.total_cost_usd = apply_f64_delta(record.total_cost_usd, delta.total_cost_usd);
+    }
+
+    pub(crate) fn rebuild_usage_stats(
+        &self,
+        contributions: &BTreeMap<String, ApiKeyUsageContribution>,
+    ) {
+        let mut index = self
+            .index
+            .write()
+            .expect("auth api key snapshot repository lock");
+        for record in index.export_by_api_key_id.values_mut() {
+            record.total_requests = 0;
+            record.total_tokens = 0;
+            record.total_cost_usd = 0.0;
+        }
+
+        for (api_key_id, contribution) in contributions {
+            let Some(record) = index.export_by_api_key_id.get_mut(api_key_id) else {
+                continue;
+            };
+            record.total_requests = clamp_i64_to_u64(contribution.total_requests);
+            record.total_tokens = clamp_i64_to_u64(contribution.total_tokens);
+            record.total_cost_usd = contribution.total_cost_usd.max(0.0);
+        }
+    }
+}
+
+fn clamp_i64_to_u64(value: i64) -> u64 {
+    u64::try_from(value).unwrap_or_default()
+}
+
+fn apply_i64_delta_to_u64(current: u64, delta: i64) -> u64 {
+    clamp_i64_to_u64(
+        i64::try_from(current)
+            .unwrap_or(i64::MAX)
+            .saturating_add(delta),
+    )
+}
+
+fn apply_f64_delta(current: f64, delta: f64) -> f64 {
+    let next = current + delta;
+    if next.is_finite() {
+        next.max(0.0)
+    } else {
+        current.max(0.0)
+    }
 }
 
 #[async_trait]