fix: audit fixes for websearch, notifications, and channel pricing

P0: fix wildcard matching test assertion (config order, not longest prefix)
P0: add TotalRecharged to auth cache snapshot (v5) for percentage threshold
P1: move pricing rules into per-platform sections in ChannelsView
P1: populate account name cache when editing existing channel rules
P1: sanitize email subject headers to prevent SMTP injection
P1: make Redis INCR+EXPIRE idempotent for rate limiting
P1: deep copy FeaturesConfig in Channel.Clone()
P2: clean up stale email="" placeholder comments
P2: replace log.Printf with slog in email_service.go

backend/internal/service/api_key_auth_cache.go

@@ -42,6 +42,7 @@ type APIKeyAuthUserSnapshot struct {
 	BalanceNotifyThresholdType string             `json:"balance_notify_threshold_type"`
 	BalanceNotifyThreshold     *float64           `json:"balance_notify_threshold,omitempty"`
 	BalanceNotifyExtraEmails   []NotifyEmailEntry `json:"balance_notify_extra_emails,omitempty"`
+	TotalRecharged             float64            `json:"total_recharged"`
 }
 
 // APIKeyAuthGroupSnapshot 分组快照