Add macOS build helper script

Adds a root-level `build.sh` for configuring and building Nebula Browser with CMake on macOS, including clean and configure-only modes. Also removes an unused `Trim` helper from the extension manager.

src/extensions/extension_manager.cpp

@@ -26,16 +26,6 @@ std::string ReadFile(const std::filesystem::path& path) {
     return buffer.str();
 }
 
-std::string Trim(std::string value) {
-    while (!value.empty() && std::isspace(static_cast<unsigned char>(value.front()))) {
-        value.erase(value.begin());
-    }
-    while (!value.empty() && std::isspace(static_cast<unsigned char>(value.back()))) {
-        value.pop_back();
-    }
-    return value;
-}
-
 std::string ToLowerAscii(std::string value) {
     std::transform(value.begin(), value.end(), value.begin(), [](unsigned char ch) {
         return static_cast<char>(std::tolower(ch));