Add GPU serial number extraction for NVIDIA diagnostics

Parse inventory/output.log to extract GPU serial numbers from lspci output,
expose them via serials API, and add GPU category to web UI.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

internal/server/handlers.go

@@ -391,6 +391,24 @@ func (s *Server) handleGetSerials(w http.ResponseWriter, r *http.Request) {
 			})
 		}
 
+		// GPUs
+		for _, gpu := range result.Hardware.GPUs {
+			if gpu.SerialNumber == "" {
+				continue
+			}
+			model := gpu.Model
+			if model == "" {
+				model = "GPU"
+			}
+			serials = append(serials, SerialEntry{
+				Component:    model,
+				Location:     gpu.Slot,
+				SerialNumber: gpu.SerialNumber,
+				Manufacturer: gpu.Manufacturer,
+				Category:     "GPU",
+			})
+		}
+
 		// PCIe devices
 		for _, pcie := range result.Hardware.PCIeDevices {
 			if pcie.SerialNumber == "" {

internal/server/handlers_gpu_test.go

@@ -0,0 +1,132 @@
+package server
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"git.mchus.pro/mchus/logpile/internal/models"
+)
+
+func TestHandleGetSerials_WithGPUs(t *testing.T) {
+	// Create test server with GPU data
+	srv := &Server{}
+
+	testResult := &models.AnalysisResult{
+		Hardware: &models.HardwareConfig{
+			GPUs: []models.GPU{
+				{
+					Slot:         "GPUSXM1",
+					Model:        "NVIDIA Device 2335",
+					Manufacturer: "NVIDIA Corporation",
+					SerialNumber: "48:B0:2D:BB:8E:51:9E:E5",
+					Firmware:     "96.00.D0.00.03",
+					BDF:          "0000:3a:00.0",
+				},
+				{
+					Slot:         "GPUSXM2",
+					Model:        "NVIDIA Device 2335",
+					Manufacturer: "NVIDIA Corporation",
+					SerialNumber: "48:B0:2D:EE:DA:27:CF:78",
+					Firmware:     "96.00.D0.00.03",
+					BDF:          "0000:18:00.0",
+				},
+			},
+		},
+	}
+
+	srv.SetResult(testResult)
+
+	// Create request
+	req := httptest.NewRequest("GET", "/api/serials", nil)
+	w := httptest.NewRecorder()
+
+	// Call handler
+	srv.handleGetSerials(w, req)
+
+	// Check response
+	if w.Code != http.StatusOK {
+		t.Errorf("Expected status 200, got %d", w.Code)
+	}
+
+	// Parse response
+	var serials []struct {
+		Component    string `json:"component"`
+		Location     string `json:"location,omitempty"`
+		SerialNumber string `json:"serial_number"`
+		Manufacturer string `json:"manufacturer,omitempty"`
+		Category     string `json:"category"`
+	}
+
+	if err := json.NewDecoder(w.Body).Decode(&serials); err != nil {
+		t.Fatalf("Failed to decode response: %v", err)
+	}
+
+	// Check that we have GPU entries
+	gpuCount := 0
+	for _, s := range serials {
+		if s.Category == "GPU" {
+			gpuCount++
+			t.Logf("Found GPU: %s (%s) S/N: %s", s.Component, s.Location, s.SerialNumber)
+
+			// Verify fields are set
+			if s.SerialNumber == "" {
+				t.Errorf("GPU serial number is empty")
+			}
+			if s.Location == "" {
+				t.Errorf("GPU location is empty")
+			}
+			if s.Manufacturer == "" {
+				t.Errorf("GPU manufacturer is empty")
+			}
+		}
+	}
+
+	if gpuCount != 2 {
+		t.Errorf("Expected 2 GPUs in serials, got %d", gpuCount)
+	}
+}
+
+func TestHandleGetSerials_WithoutGPUSerials(t *testing.T) {
+	// Create test server with GPUs but no serial numbers
+	srv := &Server{}
+
+	testResult := &models.AnalysisResult{
+		Hardware: &models.HardwareConfig{
+			GPUs: []models.GPU{
+				{
+					Slot:         "GPU0",
+					Model:        "Some GPU",
+					Manufacturer: "Vendor",
+					SerialNumber: "", // No serial number
+				},
+			},
+		},
+	}
+
+	srv.SetResult(testResult)
+
+	// Create request
+	req := httptest.NewRequest("GET", "/api/serials", nil)
+	w := httptest.NewRecorder()
+
+	// Call handler
+	srv.handleGetSerials(w, req)
+
+	// Parse response
+	var serials []struct {
+		Category string `json:"category"`
+	}
+
+	if err := json.NewDecoder(w.Body).Decode(&serials); err != nil {
+		t.Fatalf("Failed to decode response: %v", err)
+	}
+
+	// Check that GPUs without serial numbers are not included
+	for _, s := range serials {
+		if s.Category == "GPU" {
+			t.Error("GPU without serial number should not be included in serials list")
+		}
+	}
+}