fix(data): 同步模型调用次数至 global_models 读模型

- 模型列表改为读取 global_models.usage_count，避免每次扫描 usage 明细表
- 通过历史 backfill 与 usage upsert delta 维护该读模型
- 详情页保留实时 facts 兜底，统一排除 pending/streaming 状态

crates/aether-data/backfills/20260505120000_rebuild_global_model_usage_count.sql

@@ -0,0 +1,25 @@
+WITH aggregated AS (
+    SELECT
+        usage.model,
+        COUNT(*)::BIGINT AS usage_count
+    FROM usage_billing_facts AS usage
+    WHERE usage.model IS NOT NULL
+      AND BTRIM(usage.model) <> ''
+      AND usage.status NOT IN ('pending', 'streaming')
+    GROUP BY usage.model
+),
+refreshed AS (
+    SELECT
+        gm.id,
+        COALESCE(aggregated.usage_count, 0)::BIGINT AS usage_count
+    FROM global_models AS gm
+    LEFT JOIN aggregated
+      ON aggregated.model = gm.name
+)
+UPDATE global_models AS gm
+SET
+    usage_count = refreshed.usage_count,
+    updated_at = NOW()
+FROM refreshed
+WHERE gm.id = refreshed.id
+  AND COALESCE(gm.usage_count, 0) <> refreshed.usage_count;