feat: paginate dashboard clients and proxies via API v2 (#5354)

Move the frps dashboard Clients and Proxies views to the paginated
/api/v2/clients and /api/v2/proxies endpoints instead of fetching all
data at once, and extend server-side proxy search so the search box
keeps working under pagination.

Frontend:
- Add V2Envelope/V2Page types and getV2 HTTP helper to api/http.ts
- Add v2 paginated fetch functions to api/client.ts and api/proxy.ts
- Add ClientV2Info and ProxyV2Info types for v2 API responses
- Rewrite Clients.vue with server-side pagination, status/user search
  filtering, and ElPagination component
- Rewrite Proxies.vue with server-side pagination, type tabs, client
  dropdown filter, and a search box that passes q to the API
- Default page size 10, selectable sizes [10, 20, 50, 100]

Backend:
- Extend /api/v2/proxies q matching to also cover online proxy spec
  fields: TCP/UDP remotePort and HTTP/HTTPS/TCPMux customDomains and
  subdomain, so dashboard search no longer needs to scan every page
- Add controller_v2 tests for the new spec-field matching

web/frps/src/api/proxy.ts

@@ -1,7 +1,10 @@
-import { http } from './http'
+import { buildQueryString, http } from './http'
+import type { V2Page } from './http'
 import type {
   GetProxyResponse,
+  ProxyListV2Params,
   ProxyStatsInfo,
+  ProxyV2Info,
   TrafficResponse,
 } from '../types/proxy'
 
@@ -9,6 +12,40 @@ export const getProxiesByType = (type: string) => {
   return http.get<GetProxyResponse>(`../api/proxy/${type}`)
 }
 
+export const getProxiesV2 = async (params: ProxyListV2Params = {}) => {
+  const page = await http.getV2<V2Page<ProxyV2Info>>(
+    `../api/v2/proxies${buildQueryString({
+      page: params.page,
+      pageSize: params.pageSize,
+      status:
+        params.status && params.status !== 'all' ? params.status : undefined,
+      q: params.q || undefined,
+      type: params.type || undefined,
+      user: params.user,
+      clientID: params.clientID || undefined,
+    })}`,
+  )
+
+  return {
+    ...page,
+    items: page.items.map(toLegacyProxyStats),
+  }
+}
+
+const toLegacyProxyStats = (proxy: ProxyV2Info): ProxyStatsInfo => ({
+  name: proxy.name,
+  type: proxy.type,
+  conf: proxy.spec,
+  user: proxy.user,
+  clientID: proxy.clientID,
+  todayTrafficIn: proxy.status.todayTrafficIn,
+  todayTrafficOut: proxy.status.todayTrafficOut,
+  curConns: proxy.status.curConns,
+  lastStartTime: proxy.status.lastStartTime,
+  lastCloseTime: proxy.status.lastCloseTime,
+  status: proxy.status.phase,
+})
+
 export const getProxy = (type: string, name: string) => {
   return http.get<ProxyStatsInfo>(`../api/proxy/${type}/${name}`)
 }