feat: move test buttons to right panel, add user auth dialog for reports

Move Start/Stop/Report buttons from the middle panel to the top of
TestPanelView (automated tests section), matching the old application
layout. Remove inline Operator/Client text fields — operator identity
now comes from a UserCheckDialog (username/password) shown before the
existing ReportDialog. Add credential storage to ConfigurationService.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Services/IConfigurationService.cs

@@ -62,5 +62,16 @@ namespace HC_APTBS.Services
 
         /// <summary>Saves updated sensor calibration data to <c>sensors.xml</c>.</summary>
         void SaveSensors();
+
+        // ── Users ─────────────────────────────────────────────────────────────────
+
+        /// <summary>Validates a username/password pair against stored credentials.</summary>
+        bool ValidateUser(string username, string password);
+
+        /// <summary>Returns all stored user credentials as a dictionary.</summary>
+        IReadOnlyDictionary<string, string> GetUsers();
+
+        /// <summary>Replaces all stored user credentials and persists them.</summary>
+        void UpdateUsers(Dictionary<string, string> users);
     }
 }

Services/Impl/ConfigurationService.cs

@@ -94,7 +94,8 @@ namespace HC_APTBS.Services.Impl
                     new XElement("ReportLogoPath",          Settings.ReportLogoPath),
                     new XElement("KLinePort",               Settings.KLinePort),
                     new XElement("Language",                Settings.Language),
-                    new XElement("Relations",               RpmVoltageRelation.Serialise(Settings.Relations))
+                    new XElement("Relations",               RpmVoltageRelation.Serialise(Settings.Relations)),
+                    new XElement("Users",                   Settings.Users)
                 );
                 new XDocument(root).Save(ConfigXml);
                 SaveSensors();
@@ -355,6 +356,7 @@ namespace HC_APTBS.Services.Impl
                 TryString(r, "KLinePort",         v => _settings.KLinePort             = v);
                 TryString(r, "Language",          v => _settings.Language              = v);
                 TryString(r, "Relations",         v => _settings.Relations             = RpmVoltageRelation.Deserialise(v));
+                TryString(r, "Users",            v => _settings.Users                = v);
             }
             catch (Exception ex)
             {
@@ -640,6 +642,46 @@ namespace HC_APTBS.Services.Impl
             try { var v = root.Element(name)?.Value; if (v != null) assign(v); }
             catch { }
         }
+
+        // ── Users ─────────────────────────────────────────────────────────────────
+
+        /// <inheritdoc/>
+        public bool ValidateUser(string username, string password)
+        {
+            if (string.IsNullOrEmpty(username) || string.IsNullOrEmpty(password))
+                return false;
+
+            string check = username + ":" + password;
+            foreach (string entry in Settings.Users.Split(','))
+            {
+                if (entry == check) return true;
+            }
+            return false;
+        }
+
+        /// <inheritdoc/>
+        public IReadOnlyDictionary<string, string> GetUsers()
+        {
+            var dict = new Dictionary<string, string>();
+            foreach (string kv in Settings.Users.Split(','))
+            {
+                string[] parts = kv.Split(':');
+                if (parts.Length == 2 && parts[0].Length > 0)
+                    dict[parts[0]] = parts[1];
+            }
+            return dict;
+        }
+
+        /// <inheritdoc/>
+        public void UpdateUsers(Dictionary<string, string> users)
+        {
+            var entries = new List<string>(users.Count);
+            foreach (var kv in users)
+                entries.Add(kv.Key + ":" + kv.Value);
+
+            Settings.Users = string.Join(",", entries);
+            SaveSettings();
+        }
     }
 
     // ── XPath extension shim ──────────────────────────────────────────────────────