Add box3d build script for Linux + macOS

vendor/box3d/src/build.sh

@@ -0,0 +1,32 @@
+#!/usr/bin/env bash
+
+# Detect OS
+if [[ "$OSTYPE" == "darwin"* ]]; then
+	OS="darwin"
+elif [[ "$OSTYPE" == "linux-gnu"* ]]; then
+	OS="linux"
+else
+	echo "Error: Unsupported operating system: $OSTYPE"
+	exit 1
+fi
+
+# Detect architecture
+ARCH=$(uname -m)
+case "$ARCH" in
+	x86_64|amd64)
+		ARCH="amd64"
+		;;
+	arm64|aarch64)
+		ARCH="arm64"
+		;;
+	*)
+		echo "Error: Unsupported architecture: $ARCH"
+		exit 1
+		;;
+esac
+
+LIB_DIR="../lib/${OS}-${ARCH}"
+mkdir -p "$LIB_DIR"
+cc -c -O2 -std=c17 -fPIC -Iinclude src/*.c
+ar rcs "$LIB_DIR/libbox3d.a" *.o
+rm -f *.o