fix(saas): add ::bigint cast to all SUM() aggregates for PG NUMERIC compat

PostgreSQL SUM() on bigint returns NUMERIC, causing sqlx decode errors
when Rust expects i64/Option<i64>. Root cause: key_pool.rs
select_best_key() token_count SUM was missing ::bigint, causing
DATABASE_ERROR on every relay request.

Fixed in 4 files:
- relay/key_pool.rs: SUM(token_count) — root cause of relay failure
- relay/service.rs: SUM(remaining_rpm) in sort_candidates_by_quota
- account/handlers.rs: SUM(input/output_tokens) in dashboard stats
- workers/aggregate_usage.rs: SUM(input/output_tokens) in aggregation

crates/zclaw-saas/src/account/handlers.rs

@@ -194,8 +194,8 @@ pub async fn dashboard_stats(
     let today_row: DashboardTodayRow = sqlx::query_as(
         "SELECT
             (SELECT COUNT(*) FROM relay_tasks WHERE created_at >= $1 AND created_at < $2) as tasks_today,
-            COALESCE((SELECT SUM(input_tokens) FROM usage_records WHERE created_at >= $1 AND created_at < $2), 0) as tokens_input,
+            COALESCE((SELECT SUM(input_tokens) FROM usage_records WHERE created_at >= $1 AND created_at < $2), 0)::bigint as tokens_input,
-            COALESCE((SELECT SUM(output_tokens) FROM usage_records WHERE created_at >= $1 AND created_at < $2), 0) as tokens_output"
+            COALESCE((SELECT SUM(output_tokens) FROM usage_records WHERE created_at >= $1 AND created_at < $2), 0)::bigint as tokens_output"
     ).bind(&today_start).bind(&tomorrow_start).fetch_one(&state.db).await?;
 
     Ok(Json(serde_json::json!({

crates/zclaw-saas/src/relay/key_pool.rs

@@ -83,7 +83,7 @@ pub async fn select_best_key(db: &PgPool, provider_id: &str, enc_key: &[u8; 32])
         sqlx::query_as(
             "SELECT pk.id, pk.key_value, pk.priority, pk.max_rpm, pk.max_tpm,
                     COALESCE(SUM(uw.request_count), 0)::bigint,
-                    COALESCE(SUM(uw.token_count), 0)
+                    COALESCE(SUM(uw.token_count), 0)::bigint
              FROM provider_keys pk
              LEFT JOIN key_usage_window uw ON pk.id = uw.key_id
                AND uw.window_minute >= to_char(NOW() - INTERVAL '1 minute', 'YYYY-MM-DDTHH24:MI')

crates/zclaw-saas/src/relay/service.rs

@@ -648,7 +648,7 @@ pub async fn sort_candidates_by_quota(
         let quota_rows: Vec<(String, i64)> = match sqlx::query_as(
             r#"
             SELECT pk.provider_id,
-                   SUM(COALESCE(pk.max_rpm, 999999) - COALESCE(uw.request_count, 0)) AS remaining_rpm
+                   SUM(COALESCE(pk.max_rpm, 999999) - COALESCE(uw.request_count, 0))::bigint AS remaining_rpm
             FROM provider_keys pk
             LEFT JOIN key_usage_window uw ON pk.id = uw.key_id
                 AND uw.window_minute >= to_char(NOW() - INTERVAL '1 minute', 'YYYY-MM-DDTHH24:MI')

crates/zclaw-saas/src/workers/aggregate_usage.rs

@@ -56,8 +56,8 @@ async fn aggregate_single_account(db: &PgPool, account_id: &str) -> SaasResult<(
         .with_nanosecond(0).unwrap_or(now);
 
     let aggregated: Option<(i64, i64, i64)> = sqlx::query_as(
-        "SELECT COALESCE(SUM(input_tokens), 0), \
+        "SELECT COALESCE(SUM(input_tokens), 0)::bigint, \
-                COALESCE(SUM(output_tokens), 0), \
+                COALESCE(SUM(output_tokens), 0)::bigint, \
                 COUNT(*) \
          FROM usage_records \
          WHERE account_id = $1 AND created_at >= $2 AND status = 'success'"