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>

web/static/js/app.js

@@ -1079,6 +1079,7 @@ function renderSerials(serials) {
         'CPU': 'Процессор',
         'Memory': 'Память',
         'Storage': 'Накопитель',
+        'GPU': 'Видеокарта',
         'PCIe': 'PCIe',
         'Network': 'Сеть',
         'PSU': 'БП',