Add Comment, Like, Post, and User entities

backend/services/PostService/src/PostService.Domain/Entities/Comment.cs

@@ -0,0 +1,19 @@
+namespace PostService.Domain.Entities;
+
+public class Comment
+{
+    public Guid CommentId { get; private set; }
+    public Guid PostId { get; private set; }
+    public Guid UserId { get; private set; }
+    public string Content { get; private set; }
+    public DateTime CreatedAt { get; private set; }
+
+    public Comment(Guid commentId, Guid postId, Guid userId, string content)
+    {
+        CommentId = commentId;
+        PostId = postId;
+        UserId = userId;
+        Content = content;
+        CreatedAt = DateTime.UtcNow;
+    }
+}

backend/services/PostService/src/PostService.Domain/Entities/Like.cs

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+namespace PostService.Domain.Entities;
+
+public class Like
+{
+    public Guid LikeId { get; private set; }
+    public Guid PostId { get; private set; }
+    public Guid UserId { get; private set; }
+    public DateTime CreatedAt { get; private set; }
+
+    public Like(Guid likeId, Guid postId, Guid userId)
+    {
+        LikeId = likeId;
+        PostId = postId;
+        UserId = userId;
+        CreatedAt = DateTime.UtcNow;
+    }
+}

backend/services/PostService/src/PostService.Domain/Entities/Post.cs

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+namespace PostService.Domain.Entities;
+
+public class Post
+{
+    public Guid PostId { get; private set; }
+    public Guid UserId { get; private set; }
+    public string Title { get; private set; }
+    public string Content { get; private set; }
+    public string ImageUrl { get; private set; }
+    public int LikeCount { get; private set; }
+    public int CommentCount { get; private set; }
+    public DateTime CreatedAt { get; private set; }
+
+    public Post(Guid postId, Guid userId, string title, string content, string imageUrl)
+    {
+        PostId = postId;
+        UserId = userId;
+        Title = title;
+        Content = content;
+        ImageUrl = imageUrl;
+        LikeCount = 0;
+        CommentCount = 0;
+        CreatedAt = DateTime.UtcNow;
+    }
+
+    public void IncrementCommentCount() => CommentCount++;
+
+    public void IncrementLikeCount() => LikeCount++;
+}

backend/services/PostService/src/PostService.Domain/Entities/User.cs

@@ -0,0 +1,21 @@
+namespace PostService.Domain.Entities;
+
+public class User
+{
+    public Guid UserId { get; private set; }
+    public string FirstName { get; private set; }
+    public string LastName { get; private set; }
+    public string Username { get; private set; }
+    public string ImageUrl { get; private set; }
+    public DateTime CreatedAt { get; private set; }
+
+    public User(Guid userId, string firstName, string lastName, string username, string imageUrl)
+    {
+        UserId = userId;
+        FirstName = firstName;
+        LastName = lastName;
+        Username = username;
+        ImageUrl = imageUrl;
+        CreatedAt = DateTime.UtcNow;
+    }
+}