Initial commit: SSH Manager (backend + frontend)

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/src/main/java/com/sshmanager/entity/User.java

@@ -0,0 +1,35 @@
+package com.sshmanager.entity;
+
+import lombok.Data;
+import lombok.NoArgsConstructor;
+import lombok.AllArgsConstructor;
+
+import javax.persistence.*;
+import java.time.Instant;
+
+@Data
+@NoArgsConstructor
+@AllArgsConstructor
+@Entity
+@Table(name = "users")
+public class User {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    @Column(nullable = false, unique = true, length = 50)
+    private String username;
+
+    @Column(nullable = false, length = 255)
+    private String passwordHash;
+
+    @Column(length = 100)
+    private String displayName;
+
+    @Column(nullable = false)
+    private Instant createdAt = Instant.now();
+
+    @Column(nullable = false)
+    private Instant updatedAt = Instant.now();
+}