many fixes and improvements - rework for modules/ and common/

feat(emailer): add Postmark and Resend providers

backend/Modules/Identity/Models/Result.cs

@@ -0,0 +1,49 @@
+namespace Hutopy.Modules.Identity.Models;
+
+public class Result(
+    bool succeeded, 
+    IEnumerable<string> errors)
+{
+    public bool Succeeded { get; init; } = succeeded;
+    public string[] Errors { get; init; } = errors.ToArray();
+    
+    public static Result Success()
+    {
+        return new Result(true, Array.Empty<string>());
+    }
+
+    public static Result Failure(IEnumerable<string> errors)
+    {
+        return new Result(false, errors);
+    }
+}
+
+public class Result<T>(
+    T? value,
+    bool succeeded, 
+    IEnumerable<string> errors)
+{
+    public bool Succeeded { get; init; } = succeeded;
+    public string[] Errors { get; init; } = errors.ToArray();
+    public T? Value { get; set; } = value;
+    
+    public T GetValueOrDefault()
+    {
+        return Value ?? default(T)!;
+    }
+    
+    public string GetErrorsAsString()
+    {
+        return Errors.Length == 0 ? string.Empty : string.Join(", ", Errors);
+    }
+
+    public static Result<T> Success(T value)
+    {
+        return new Result<T>(value, true, Array.Empty<string>());
+    }
+
+    public static Result<T> Failure(T value, IEnumerable<string> errors)
+    {
+        return new Result<T>(value, false, errors);
+    }
+}