feat(ui): client-realtime-speed (#5687)

* refactor(inbounds): extract TRAFFIC_POLL_INTERVAL_S to shared util

* feat(clients): derive per-client live speed from traffic WebSocket deltas

* feat(clients): render speed column and mobile card line

* i18n(clients): add pages.clients.speed key to all 13 locales

frontend/src/pages/inbounds/useInbounds.ts

@@ -13,6 +13,7 @@ import { OnlinesSchema, OnlineByNodeSchema, ActiveInboundsByNodeSchema } from '@
 import { DefaultsPayloadSchema, type DefaultsPayload } from '@/schemas/defaults';
 
 import type { InboundSpeedEntry } from './list/types';
+import { TRAFFIC_POLL_INTERVAL_S } from '@/lib/traffic/poll-interval';
 
 export interface SubSettings {
   enable: boolean;
@@ -28,10 +29,6 @@ export interface SubSettings {
 
 type DBInboundInstance = InstanceType<typeof DBInbound>;
 
-// Server-side traffic polling interval in seconds. XrayTrafficJob broadcasts
-// deltas accumulated over this window, so dividing by it yields bytes/sec.
-const TRAFFIC_POLL_INTERVAL_S = 5;
-
 // Speed is delta-derived, so it can't be recomputed until the first poll after
 // mount; navigating away and back would otherwise blank the column for up to one
 // poll. Cache the last speed map across mounts (module scope) and reseed from it