feat(websearch): settings UI overhaul and quota improvements

- Remove Priority field, auto load-balance by quota remaining
- Replace QuotaRefreshInterval (daily/weekly/monthly) with SubscribedAt
  (subscription date, monthly lazy refresh via Redis TTL)
- Add collapsible provider cards, API key show/copy, usage progress bar
- Add test endpoint (POST /web-search-emulation/test) bypassing quota
- Wire WebSearchManagerBuilder on startup (was never called before)
- Fix nextMonthlyReset day-of-month overflow (Jan 31 → Feb 28)
- Fix non-deterministic sort in selectByQuotaWeight
- Map ProxyID in builder for provider-level proxy tracking
- Fix frontend timezone drift in subscribed_at date picker
- Fix provider deletion index shift for expandedProviders state

backend/internal/server/http.go

@@ -2,12 +2,14 @@
 package server
 
 import (
+	"context"
 	"log"
 	"net/http"
 	"time"
 
 	"github.com/Wei-Shaw/sub2api/internal/config"
 	"github.com/Wei-Shaw/sub2api/internal/handler"
+	"github.com/Wei-Shaw/sub2api/internal/pkg/websearch"
 	middleware2 "github.com/Wei-Shaw/sub2api/internal/server/middleware"
 	"github.com/Wei-Shaw/sub2api/internal/service"
 
@@ -56,6 +58,34 @@ func ProvideRouter(
 		}
 	}
 
+	// Wire up websearch Manager builder so it initializes on startup and rebuilds on config save.
+	settingService.SetWebSearchManagerBuilder(context.Background(), func(cfg *service.WebSearchEmulationConfig) {
+		if cfg == nil || !cfg.Enabled || len(cfg.Providers) == 0 {
+			service.SetWebSearchManager(nil)
+			return
+		}
+		configs := make([]websearch.ProviderConfig, 0, len(cfg.Providers))
+		for _, p := range cfg.Providers {
+			if p.APIKey == "" {
+				continue
+			}
+			pc := websearch.ProviderConfig{
+				Type:       p.Type,
+				APIKey:     p.APIKey,
+				QuotaLimit: p.QuotaLimit,
+				ExpiresAt:  p.ExpiresAt,
+			}
+			if p.SubscribedAt != nil {
+				pc.SubscribedAt = p.SubscribedAt
+			}
+			if p.ProxyID != nil {
+				pc.ProxyID = *p.ProxyID
+			}
+			configs = append(configs, pc)
+		}
+		service.SetWebSearchManager(websearch.NewManager(configs, redisClient))
+	})
+
 	return SetupRouter(r, handlers, jwtAuth, adminAuth, apiKeyAuth, apiKeyService, subscriptionService, opsService, settingService, cfg, redisClient)
 }
 

backend/internal/server/routes/admin.go

@@ -410,6 +410,7 @@ func registerSettingsRoutes(admin *gin.RouterGroup, h *handler.Handlers) {
 		// Web Search 模拟配置
 		adminSettings.GET("/web-search-emulation", h.Admin.Setting.GetWebSearchEmulationConfig)
 		adminSettings.PUT("/web-search-emulation", h.Admin.Setting.UpdateWebSearchEmulationConfig)
+		adminSettings.POST("/web-search-emulation/test", h.Admin.Setting.TestWebSearchEmulation)
 	}
 }