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_impl.go

@@ -13,7 +13,7 @@ import (
 	"github.com/dgraph-io/ristretto"
 )
 
-const apiKeyAuthSnapshotVersion = 4 // v4: added balance notification fields to UserSnapshot
+const apiKeyAuthSnapshotVersion = 5 // v5: added TotalRecharged for percentage threshold
 
 type apiKeyAuthCacheConfig struct {
 	l1Size        int
@@ -230,6 +230,7 @@ func (s *APIKeyService) snapshotFromAPIKey(apiKey *APIKey) *APIKeyAuthSnapshot {
 			BalanceNotifyThresholdType: apiKey.User.BalanceNotifyThresholdType,
 			BalanceNotifyThreshold:     apiKey.User.BalanceNotifyThreshold,
 			BalanceNotifyExtraEmails:   apiKey.User.BalanceNotifyExtraEmails,
+			TotalRecharged:             apiKey.User.TotalRecharged,
 		},
 	}
 	if apiKey.Group != nil {
@@ -291,6 +292,7 @@ func (s *APIKeyService) snapshotToAPIKey(key string, snapshot *APIKeyAuthSnapsho
 			BalanceNotifyThresholdType: snapshot.User.BalanceNotifyThresholdType,
 			BalanceNotifyThreshold:     snapshot.User.BalanceNotifyThreshold,
 			BalanceNotifyExtraEmails:   snapshot.User.BalanceNotifyExtraEmails,
+			TotalRecharged:             snapshot.User.TotalRecharged,
 		},
 	}
 	if snapshot.Group != nil {