新增Linux GPU监控功能

参考了nezha-agent。实现了Linux服务器下NVIDIA显卡的监控。
通过 --gpu 参数启用显卡监控功能。
支持多显卡，显卡使用率，显存使用率监控
实现了AMD显卡的监控，但是未经过测试

monitoring/unit/gpu_detailed_test.go

@@ -0,0 +1,67 @@
+package monitoring
+
+import (
+	"testing"
+)
+
+func TestDetailedGPUDetection(t *testing.T) {
+	models, err := GetDetailedGPUHost()
+	if err != nil {
+		t.Logf("Detailed GPU detection failed (may be normal on non-Linux or non-GPU systems): %v", err)
+		return
+	}
+
+	t.Logf("Detected GPUs: %v", models)
+
+	if len(models) > 0 {
+		usage, err := GetDetailedGPUState()
+		if err != nil {
+			t.Logf("GPU state collection failed: %v", err)
+		} else {
+			t.Logf("GPU usage: %v", usage)
+		}
+
+		// 测试详细信息获取
+		detailedInfo, err := GetDetailedGPUInfo()
+		if err != nil {
+			t.Logf("GPU detailed info collection failed: %v", err)
+		} else {
+			for i, info := range detailedInfo {
+				t.Logf("GPU %d: %s - Memory: %dMB/%dMB, Usage: %.1f%%, Temp: %d°C",
+					i, info.Name, info.MemoryUsed, info.MemoryTotal, info.Utilization, info.Temperature)
+			}
+		}
+	}
+}
+
+func TestDetailedGPUInfo(t *testing.T) {
+	detailedInfo, err := GetDetailedGPUInfo()
+	if err != nil {
+		t.Logf("GPU detailed info test failed (may be normal): %v", err)
+		return
+	}
+
+	if len(detailedInfo) == 0 {
+		t.Log("No detailed GPU info available")
+		return
+	}
+
+	for i, info := range detailedInfo {
+		t.Logf("GPU %d Details:", i)
+		t.Logf("  Name: %s", info.Name)
+		t.Logf("  Memory Total: %d MB", info.MemoryTotal)
+		t.Logf("  Memory Used: %d MB", info.MemoryUsed)
+		t.Logf("  Memory Free: %d MB", info.MemoryFree)
+		t.Logf("  Utilization: %.1f%%", info.Utilization)
+		t.Logf("  Temperature: %d°C", info.Temperature)
+
+		// 验证数据的合理性
+		if info.MemoryTotal > 0 && info.MemoryUsed+info.MemoryFree != info.MemoryTotal {
+			t.Logf("Warning: Memory usage calculation may be inconsistent for %s", info.Name)
+		}
+
+		if info.Utilization < 0 || info.Utilization > 100 {
+			t.Errorf("Invalid utilization value for %s: %.1f%%", info.Name, info.Utilization)
+		}
+	}
+}