feat: dark mode preference (#1887)

* Client settings persisted locally

* Apply dark mode preference

---------

Co-authored-by: smtp4dev-automation <noreply@github.com>

Author: rnwood

.vscode/launch.json

@@ -11,7 +11,7 @@
             // If you have changed target frameworks, make sure to update the program path.
             "program": "${workspaceFolder}/Rnwood.Smtp4dev/bin/Debug/net8.0/Rnwood.Smtp4dev.dll",
             "cwd": "${workspaceFolder}/Rnwood.Smtp4dev",
-            "args": ["--recreatedb", "--urls", "http://localhost:5000", "--basepath=/smtp4dev", "--debugsettings"],
+            "args": ["--recreatedb", "--urls", "http://localhost:5000", "--debugsettings"],
             "stopAtEntry": false,
             "internalConsoleOptions": "openOnSessionStart",
             "preLaunchTask": "build Rnwood.Smtp4dev",

Rnwood.Smtp4dev/ApiModel/ClientSettings.cs

@@ -4,5 +4,6 @@ public class ClientSettings
     {
         public int PageSize { get; set; }
         public bool AutoViewNewMessages { get; set; }
+        public string DarkMode { get; set; }
     }
 }