Add lexer, parser and AST debug printer

Implements tokenizer for basic tokens (INT, ID, ASSIGN, PLUS, MINUS, NEWLINE, PRINT),
recursive descent parser for assignments and binary expressions, and
tree-formatted AST visualization with ast_debug().

src/main.c

@@ -1,3 +1,4 @@
+#include "frontend/parser.h"
 #include "objects/object.h"
 
 int main() {
@@ -13,20 +14,25 @@ int main() {
   items[0] = floatVar1;
   items[1] = stringVar1;
   items[2] = listVar1;
-  
+
   obj_print(allocPtr, listVar1, "");
 
   obj_free(allocPtr, stringVar1);
 
-  stringVar1 = obj_new_string(allocPtr, "Hola Mundo!"); 
+  stringVar1 = obj_new_string(allocPtr, "Hola Mundo!");
   items[1] = stringVar1;
   items[2] = stringVar1;
-  
-
 
   obj_print(allocPtr, listVar1, "");
 
   JLANG_visualize(allocPtr);
 
+  // Lexer test
+  int totalTokens = 0;
+  Token *tokens = tokenize("x = 10\ny = 5\nz = x + y\nprint z", &totalTokens);
+  printf("totalTokens=%d\n", totalTokens);
+  ASTNode* block = parse(tokens, totalTokens);
+  ast_debug(block);
+
   return 0;
 }