feat: 添加打印机管理模块，支持局域网打印

src/main/java/com/example/building/controller/PrinterController.java

@@ -0,0 +1,96 @@
+package com.example.building.controller;
+
+import com.example.building.common.Result;
+import com.example.building.entity.Printer;
+import com.example.building.service.PrinterService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.web.bind.annotation.*;
+
+import java.util.List;
+
+/**
+ * 打印机控制器
+ */
+@RestController
+@RequestMapping("/api/v1/printers")
+public class PrinterController {
+
+    @Autowired
+    private PrinterService printerService;
+
+    /**
+     * 获取打印机列表
+     */
+    @GetMapping
+    public Result<List<Printer>> getPrinters() {
+        return Result.success(printerService.list());
+    }
+
+    /**
+     * 获取默认打印机
+     */
+    @GetMapping("/default")
+    public Result<Printer> getDefaultPrinter() {
+        Printer printer = printerService.getDefaultPrinter();
+        return Result.success(printer);
+    }
+
+    /**
+     * 添加打印机
+     */
+    @PostMapping
+    public Result<Printer> addPrinter(@RequestBody Printer printer) {
+        printerService.save(printer);
+        return Result.success(printer);
+    }
+
+    /**
+     * 更新打印机
+     */
+    @PutMapping("/{id}")
+    public Result<Printer> updatePrinter(@PathVariable String id, @RequestBody Printer printer) {
+        printer.setPrinterId(id);
+        printerService.updateById(printer);
+        return Result.success(printer);
+    }
+
+    /**
+     * 删除打印机
+     */
+    @DeleteMapping("/{id}")
+    public Result<Void> deletePrinter(@PathVariable String id) {
+        printerService.removeById(id);
+        return Result.success();
+    }
+
+    /**
+     * 设置默认打印机
+     */
+    @PutMapping("/{id}/default")
+    public Result<Void> setDefaultPrinter(@PathVariable String id) {
+        // 先取消所有默认
+        List<Printer> printers = printerService.list();
+        for (Printer p : printers) {
+            if (p.getIsDefault() != null && p.getIsDefault() == 1) {
+                p.setIsDefault(0);
+                printerService.updateById(p);
+            }
+        }
+        // 设置新的默认
+        Printer printer = printerService.getById(id);
+        if (printer != null) {
+            printer.setIsDefault(1);
+            printerService.updateById(printer);
+        }
+        return Result.success();
+    }
+
+    /**
+     * 打印订单
+     */
+    @PostMapping("/print/{orderId}")
+    public Result<Void> printOrder(@PathVariable String orderId) {
+        printerService.printOrder(orderId);
+        return Result.success();
+    }
+}