feat: begin binary tree implementation

src/tree/node.h

@@ -0,0 +1,13 @@
+#ifndef VIETER_BALANCED_TREE_NODE
+#define VIETER_BALANCED_TREE_NODE
+
+#include <stdint.h>
+
+typedef struct vieter_tree_node {
+    uint64_t key;
+    void *data;
+    struct vieter_tree_node *left;
+    struct vieter_tree_node *right;
+} vieter_tree_node;
+
+#endif

src/tree/tree.c

@@ -0,0 +1,6 @@
+#include "vieter_tree.h"
+#include "node.h"
+
+struct vieter_tree {
+    uint64_t size;
+};