fix: migrate from deprecated @GenericGenerator to @IdGeneratorType

- Update ServerIdGenerator to use @IdGeneratorType annotation (Hibernate 6.5+)
- Convert ServerIdGenerator to annotation-based custom generator
- Update Servers entity to use @ServerIdGenerator annotation
- Fix SQL reserved keyword issue: rename 'user' column to 'username'
This resolves deprecation warnings and SQL syntax errors with H2 database.

backend/src/main/java/com/hitcommunications/servermanager/model/Servers.java

@@ -0,0 +1,59 @@
+package com.hitcommunications.servermanager.model;
+
+import com.hitcommunications.servermanager.model.enums.Applications;
+import com.hitcommunications.servermanager.model.enums.DatabaseType;
+import com.hitcommunications.servermanager.model.enums.ServersType;
+import com.hitcommunications.servermanager.utils.ServerIdGenerator;
+import jakarta.persistence.*;
+import lombok.*;
+import org.hibernate.annotations.CreationTimestamp;
+import org.hibernate.annotations.UpdateTimestamp;
+
+import java.sql.Timestamp;
+
+@Entity
+@Table(name = "tab_servers")
+@AllArgsConstructor
+@NoArgsConstructor
+@Getter
+@Setter
+@Builder
+public class Servers {
+
+    @Id
+    @ServerIdGenerator
+    @Column(nullable = false, unique = true)
+    private String id;
+
+    @Column(nullable = false)
+    private String name;
+
+    @Column(nullable = false)
+    private String ip;
+
+    @Column(nullable = false)
+    private Integer port;
+
+    @Column(nullable = false, name = "username")
+    private String user;
+
+    @Column(nullable = false)
+    private String password;
+
+    @Column(nullable = false)
+    @Enumerated(EnumType.STRING)
+    private ServersType type;
+
+    @Column(nullable = false)
+    @Enumerated(EnumType.STRING)
+    private Applications application;
+
+    @Column(nullable = false)
+    @Enumerated(EnumType.STRING)
+    private DatabaseType dbType;
+
+    @CreationTimestamp
+    private Timestamp createdAt;
+    @UpdateTimestamp
+    private Timestamp updatedAt;
+}

backend/src/main/java/com/hitcommunications/servermanager/model/enums/Applications.java

@@ -0,0 +1,9 @@
+package com.hitcommunications.servermanager.model.enums;
+
+public enum Applications {
+    ASTERISK,
+    HITMANAGER,
+    HITMANAGER_V2,
+    OMNIHIT,
+    HITPHONE
+}

backend/src/main/java/com/hitcommunications/servermanager/model/enums/DatabaseType.java

@@ -0,0 +1,12 @@
+package com.hitcommunications.servermanager.model.enums;
+
+public enum DatabaseType {
+    MYSQL,
+    POSTGRESQL,
+    SQLSERVER,
+    ORACLE,
+    REDIS,
+    MONGODB,
+    MARIADB,
+    NONE
+}

backend/src/main/java/com/hitcommunications/servermanager/model/enums/ServersType.java

@@ -0,0 +1,7 @@
+package com.hitcommunications.servermanager.model.enums;
+
+public enum ServersType {
+    PRODUCTION,
+    HOMOLOGATION,
+    DATABASE
+}

backend/src/main/java/com/hitcommunications/servermanager/utils/ServerIdGenerator.java

@@ -0,0 +1,33 @@
+package com.hitcommunications.servermanager.utils;
+
+import org.hibernate.annotations.IdGeneratorType;
+import org.hibernate.engine.spi.SharedSessionContractImplementor;
+import org.hibernate.id.IdentifierGenerator;
+
+import java.io.Serializable;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.util.Random;
+
+@IdGeneratorType(ServerIdGenerator.ServerIdGeneratorImpl.class)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface ServerIdGenerator {
+
+    class ServerIdGeneratorImpl implements IdentifierGenerator {
+
+        private static final String PREFIX = "server_";
+        private static final int RANDOM_DIGITS = 12;
+        private static final Random random = new Random();
+
+        @Override
+        public Serializable generate(SharedSessionContractImplementor session, Object object) {
+            StringBuilder randomPart = new StringBuilder();
+
+            for (int i = 0; i < RANDOM_DIGITS; i++) {
+                randomPart.append(random.nextInt(10));
+            }
+
+            return PREFIX + randomPart;
+        }
+    }
+}