Add CLI flags for setup and server configuration

- Add --setup flag to create admin user
- Add --admin-user and --admin-password for setup
- Generate cryptographically random passwords for --setup
- Add --bind and --port flags for server binding
- Add BIND env var support
- Add SMTP email service for password reset
- Add password reset token storage
- Add auth header to queue/logs frontend pages
- Fix journalctl timestamp format
- Fix logs to return empty array instead of error when no entries
- Fix queue handler to return proper error message
- Hide Users/Aliases nav links when no domain selected

backend/internal/api/handlers/queue.go

@@ -20,7 +20,7 @@ func (h *QueueHandler) List(w http.ResponseWriter, r *http.Request) {
 
 	entries, err := mail.GetQueue()
 	if err != nil {
-		Error(w, http.StatusInternalServerError, "failed to get queue")
+		Error(w, http.StatusServiceUnavailable, "mail queue tools not available")
 		return
 	}