fix: NPM remote toggle auto-save, proxy resync on remote change, webhook URL as path

- Remote NPM toggle now auto-saves immediately when toggled
- Toggling npm_remote triggers proxy resync (re-creates routes with server_ip or container name)
- Webhook URL shows just the path (/api/webhook/{secret}) instead of full URL with wrong domain
- Fix tag dropdown: resolve registry ID from name before fetching tags
- Remove unused fmt import

internal/api/settings.go

@@ -2,7 +2,6 @@ package api
 
 import (
 	"context"
-	"fmt"
 	"log/slog"
 	"net/http"
 	"path/filepath"
@@ -234,6 +233,7 @@ func (s *Server) updateSettings(w http.ResponseWriter, r *http.Request) {
 	// If proxy-affecting settings changed, re-sync all proxy routes in the background.
 	proxyChanged := existing.Domain != updated.Domain ||
 		existing.ProxyProvider != updated.ProxyProvider ||
+		existing.NpmRemote != updated.NpmRemote ||
 		sslChanged
 	if proxyChanged {
 		go s.resyncAllProxies(existing, updated)
@@ -267,20 +267,13 @@ func (s *Server) getWebhookURL(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	webhookURL := ""
+	webhookPath := ""
 	if settings.WebhookSecret != "" {
-		host := settings.Domain
-		scheme := "https"
-		if host == "" {
-			// Fall back to request host for dev/local setups.
-			host = r.Host
-			scheme = "http"
-		}
-		webhookURL = fmt.Sprintf("%s://%s/api/webhook/%s", scheme, host, settings.WebhookSecret)
+		webhookPath = "/api/webhook/" + settings.WebhookSecret
 	}
 
 	respondJSON(w, http.StatusOK, map[string]string{
-		"webhook_url": webhookURL,
+		"webhook_url": webhookPath,
 	})
 }
 
@@ -292,19 +285,7 @@ func (s *Server) regenerateWebhookSecret(w http.ResponseWriter, r *http.Request)
 		return
 	}
 
-	settings, err := s.store.GetSettings()
-	if err != nil {
-		respondError(w, http.StatusInternalServerError, "failed to get settings: "+err.Error())
-		return
-	}
-
-	host := settings.Domain
-	scheme := "https"
-	if host == "" {
-		host = r.Host
-		scheme = "http"
-	}
-	webhookURL := fmt.Sprintf("%s://%s/api/webhook/%s", scheme, host, secret)
+	webhookURL := "/api/webhook/" + secret
 
 	respondJSON(w, http.StatusOK, map[string]string{
 		"webhook_url":    webhookURL,