Add src/node/* code to node:: namespace

src/node/minisketchwrapper.cpp

@@ -16,6 +16,7 @@
 #include <utility>
 #include <vector>
 
+namespace node {
 namespace {
 
 static constexpr uint32_t BITS = 32;
@@ -75,3 +76,4 @@ Minisketch MakeMinisketch32FP(size_t max_elements, uint32_t fpbits)
 {
     return Minisketch::CreateFP(BITS, Minisketch32Implementation(), max_elements, fpbits);
 }
+} // namespace node