feat(provider): add update endpoint and enforce status checks

Add `PUT /admin/providers/{id}` endpoint to allow updating provider
configurations, including status and ban details. Update synchronization
logic to exclude inactive or banned providers from routing tables to
ensure traffic is not routed to them.

internal/dto/provider.go

@@ -14,4 +14,7 @@ type ProviderDTO struct {
 	AutoBan   *bool     `json:"auto_ban,omitempty"`
 	BanReason string    `json:"ban_reason,omitempty"`
 	BanUntil  time.Time `json:"ban_until,omitempty"`
+
+	// Optional control params
+	SkipRouting bool `json:"skip_routing,omitempty"` // if true, do not add to routing tables (e.g., disabled)
 }