fix: TypeScript errors blocking production build

- Replace process.env.NODE_ENV with import.meta.env.DEV (Vite compatible)
- Fix undefined not assignable to boolean|null with nullish coalescing

frontend/src/components/test-detail/DetectionRuleChecklist.tsx

@@ -294,7 +294,7 @@ export default function DetectionRuleChecklist({ testId, user, canEdit }: Props)
                           className="flex-1 rounded border border-gray-700 bg-gray-900 px-2 py-1.5 text-xs text-gray-200 placeholder-gray-500 focus:border-indigo-500 focus:outline-none"
                         />
                         <button
-                          onClick={() => handleNotesSave(rule.id, rule.triggered)}
+                          onClick={() => handleNotesSave(rule.id, rule.triggered ?? null)}
                           disabled={evaluateMutation.isPending}
                           className="shrink-0 rounded bg-indigo-600 px-2 py-1.5 text-xs font-medium text-white hover:bg-indigo-500 disabled:opacity-50"
                         >