feat(statistics): 新增首页统计相关功能

- 新增 HomeStatsVO 作为首页统计数据传输对象，包含位置统计和位置列表
- 新增 IStatisticsService 接口及其实现类 StatisticsServiceImpl，提供首页统计数据获取方法
- 新增 StatisticsMapper 接口及对应 XML 实现位置统计和顶级位置列表的数据库查询
- 新增 StatisticsController 提供首页统计接口，支持前端获取统计数据
- 所有新增代码均为轻量级查询，避免跨分表查询带来的性能问题

ruoyi-modules/hw-rfid/src/main/java/org/dromara/rfid/controller/StatisticsController.java

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+package org.dromara.rfid.controller;
+
+import lombok.RequiredArgsConstructor;
+import org.dromara.common.core.domain.R;
+import org.dromara.common.web.core.BaseController;
+import org.dromara.rfid.domain.vo.HomeStatsVO;
+import org.dromara.rfid.service.IStatisticsService;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+/**
+ * 首页统计接口
+ */
+@RequiredArgsConstructor
+@RestController
+@RequestMapping("/rfid/statistics")
+public class StatisticsController extends BaseController {
+
+    private final IStatisticsService statisticsService;
+
+    /**
+     * 获取首页统计数据
+     */
+    @GetMapping("/home")
+    public R<HomeStatsVO> getHomeStats() {
+        return R.ok(statisticsService.getHomeStats());
+    }
+}

ruoyi-modules/hw-rfid/src/main/java/org/dromara/rfid/domain/vo/HomeStatsVO.java

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+package org.dromara.rfid.domain.vo;
+
+import lombok.Data;
+import java.io.Serial;
+import java.io.Serializable;
+import java.util.List;
+
+/**
+ * 首页统计 VO（轻量级，不查询分表数据）
+ */
+@Data
+public class HomeStatsVO implements Serializable {
+
+    @Serial
+    private static final long serialVersionUID = 1L;
+
+    /**
+     * 位置统计
+     */
+    private LocationStats locationStats;
+
+    /**
+     * 位置列表（仅展示顶级）
+     */
+    private List<LocationItem> locations;
+
+    /**
+     * 位置统计
+     */
+    @Data
+    public static class LocationStats {
+        /** 位置总数 */
+        private Long totalLocations;
+        /** 车间数量 */
+        private Long workshopCount;
+        /** 工序数量 */
+        private Long processCount;
+        /** 工位数量 */
+        private Long stationCount;
+    }
+
+    /**
+     * 位置项
+     */
+    @Data
+    public static class LocationItem {
+        private Long id;
+        private String locationCode;
+        private String locationAlias;
+        private String locationType;
+        /** 子位置数量 */
+        private Long childCount;
+    }
+}

ruoyi-modules/hw-rfid/src/main/java/org/dromara/rfid/mapper/StatisticsMapper.java

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+package org.dromara.rfid.mapper;
+
+import org.dromara.rfid.domain.vo.HomeStatsVO;
+import org.apache.ibatis.annotations.Mapper;
+import java.util.List;
+
+/**
+ * 首页统计 Mapper 接口（轻量级查询，不涉及分表）
+ */
+@Mapper
+public interface StatisticsMapper {
+
+    /**
+     * 获取位置统计
+     */
+    HomeStatsVO.LocationStats selectLocationStats();
+
+    /**
+     * 获取顶级位置列表
+     */
+    List<HomeStatsVO.LocationItem> selectTopLocations();
+}

ruoyi-modules/hw-rfid/src/main/java/org/dromara/rfid/service/IStatisticsService.java

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+package org.dromara.rfid.service;
+
+import org.dromara.rfid.domain.vo.HomeStatsVO;
+
+/**
+ * 首页统计 Service 接口
+ */
+public interface IStatisticsService {
+
+    /**
+     * 获取首页统计数据
+     */
+    HomeStatsVO getHomeStats();
+}

ruoyi-modules/hw-rfid/src/main/java/org/dromara/rfid/service/impl/StatisticsServiceImpl.java

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+package org.dromara.rfid.service.impl;
+
+import lombok.RequiredArgsConstructor;
+import org.dromara.rfid.domain.vo.HomeStatsVO;
+import org.dromara.rfid.mapper.StatisticsMapper;
+import org.dromara.rfid.service.IStatisticsService;
+import org.springframework.stereotype.Service;
+
+/**
+ * 首页统计 Service 实现（轻量级，仅查询位置表）
+ */
+@RequiredArgsConstructor
+@Service
+public class StatisticsServiceImpl implements IStatisticsService {
+
+    private final StatisticsMapper statisticsMapper;
+
+    @Override
+    public HomeStatsVO getHomeStats() {
+        HomeStatsVO vo = new HomeStatsVO();
+        // 仅查询 rfid_location 表，避免分表查询带来的性能问题
+        vo.setLocationStats(statisticsMapper.selectLocationStats());
+        vo.setLocations(statisticsMapper.selectTopLocations());
+        return vo;
+    }
+}

ruoyi-modules/hw-rfid/src/main/resources/mapper/rfid/StatisticsMapper.xml

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+<?xml version="1.0" encoding="UTF-8" ?>
+<!DOCTYPE mapper
+        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
+        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
+<mapper namespace="org.dromara.rfid.mapper.StatisticsMapper">
+
+    <!-- 位置统计（轻量级，仅查询 rfid_location 表） -->
+    <select id="selectLocationStats" resultType="org.dromara.rfid.domain.vo.HomeStatsVO$LocationStats">
+        SELECT
+            COUNT(*) as totalLocations,
+            SUM(CASE WHEN location_type = '1' THEN 1 ELSE 0 END) as workshopCount,
+            SUM(CASE WHEN location_type = '2' THEN 1 ELSE 0 END) as processCount,
+            SUM(CASE WHEN location_type = '3' THEN 1 ELSE 0 END) as stationCount
+        FROM rfid_location
+    </select>
+
+    <!-- 顶级位置列表（parent_id = 0 或 NULL） -->
+    <select id="selectTopLocations" resultType="org.dromara.rfid.domain.vo.HomeStatsVO$LocationItem">
+        SELECT
+            l.id,
+            l.location_code as locationCode,
+            l.location_alias as locationAlias,
+            l.location_type as locationType,
+            (SELECT COUNT(*) FROM rfid_location c WHERE c.parent_id = l.id) as childCount
+        FROM rfid_location l
+        WHERE l.parent_id = 0 OR l.parent_id IS NULL
+        ORDER BY l.id
+    </select>
+
+</mapper>