feat: add MaintenancePlan entity for preventive maintenance

module-mdm/src/main/java/com/ether/pms/mdm/entity/MaintenancePlan.java

@@ -0,0 +1,85 @@
+package com.ether.pms.mdm.entity;
+
+import jakarta.persistence.*;
+import lombok.Data;
+import java.time.LocalDateTime;
+import java.util.UUID;
+
+@Entity
+@Table(name = "ops_maintenance_plan")
+@Data
+public class MaintenancePlan {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.UUID)
+    private UUID id;
+
+    @Column(name = "project_id", nullable = false)
+    private UUID projectId;
+
+    @Column(name = "plan_code", nullable = false, unique = true)
+    private String planCode;
+
+    @Column(name = "plan_name", nullable = false)
+    private String planName;
+
+    @Column(name = "equipment_type")
+    private String equipmentType;
+
+    @Column(name = "trigger_type", nullable = false)
+    @Enumerated(EnumType.STRING)
+    private TriggerType triggerType;
+
+    public enum TriggerType {
+        TIME_BASED,    // 时间触发
+        HOURS_BASED,   // 运行小时触发
+        CYCLES_BASED,  // 次数触发
+        CONDITION_BASED // 条件触发
+    }
+
+    @Column(name = "trigger_value")
+    private Integer triggerValue;
+
+    @Column(name = "trigger_unit")
+    private String triggerUnit;
+
+    @Column(name = "maintenance_items", columnDefinition = "TEXT")
+    private String maintenanceItems;
+
+    @Column(name = "estimated_duration")
+    private Integer estimatedDuration;
+
+    @Column(name = "assigned_to")
+    private UUID assignedTo;
+
+    @Column(name = "sla_response_hours")
+    private Integer slaResponseHours;
+
+    @Column(name = "sla_complete_hours")
+    private Integer slaCompleteHours;
+
+    @Column(nullable = false)
+    @Enumerated(EnumType.STRING)
+    private Status status = Status.ACTIVE;
+
+    public enum Status {
+        ACTIVE, INACTIVE
+    }
+
+    @Column(name = "created_at")
+    private LocalDateTime createdAt;
+
+    @Column(name = "updated_at")
+    private LocalDateTime updatedAt;
+
+    @PrePersist
+    public void prePersist() {
+        createdAt = LocalDateTime.now();
+        updatedAt = LocalDateTime.now();
+    }
+
+    @PreUpdate
+    public void preUpdate() {
+        updatedAt = LocalDateTime.now();
+    }
+}