feat(server/stats): stats-overhaul Phase2 — 每设备归因 + GB 综合配额

服务端记账从「账户」细到「每设备」(每设备独立 dp_uuid),配额单位分钟→GB
按账户综合卡控。000015_per_device_usage 迁移(mysql+sqlite 双份):devices.dp_uuid
+ usage_device_daily 表 + plans.daily_mb。handler_grpc 按 dp_uuid 回映射
(user_id,device_id) 双写账户+每设备;usage 服务/handler 暴露 /v1/usage(/devices)。
含 sqlite_per_device / usage handler 测试。

注:此迁移 prod 已 migrate up 运行、部署二进制已内嵌;本次补提交使 git 与线上一致。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

server/cmd/server/main.go

@@ -286,6 +286,7 @@ func mountV1(r chi.Router, sqlDB *sql.DB, rdb *redis.Client, nodeSvc *nodes.Serv
 	usageStore := usage.NewStore(sqlDB)
 	usageSvc := usage.NewService(usageStore, rdb, nil, time.Hour)
 	usageHandler := usage.NewUsageHandler(usageSvc)
+	deviceUsageHandler := usage.NewDeviceUsageHandler(usageSvc)
 	adsHandler := usage.NewAdsUnlockHandler(usageSvc)
 
 	// ── Account / Plans / Notices ─────────────────────────────────────────────
@@ -364,6 +365,7 @@ func mountV1(r chi.Router, sqlDB *sql.DB, rdb *redis.Client, nodeSvc *nodes.Serv
 				})
 				protected.Post("/redeem", redeemHandler.ServeHTTP)
 				protected.Get("/usage", usageHandler.ServeHTTP)
+				protected.Get("/usage/devices", deviceUsageHandler.ServeHTTP)
 				protected.Post("/ads/unlock", adsHandler.ServeHTTP)
 				protected.Get("/plans", accountAPI.ListPlans)
 				protected.Get("/notices", accountAPI.ListNotices)