fix: Pratt parser NUD/LED akışı, Token* slicing, null guard

- ParserToken artık Token* tutuyor (object slicing önlendi)
- parseNullDenotation atom'ları tüketip ilerliyor
- parseExpression while döngüsü currentToken() ile çalışıyor
- IR: null Left/Right ve null ASTNode girişi korumalı
- source.sqt: 1/(74-63+!1)-74*2/-0.7e+10 başarıyla parse ediliyor

source.sqt

@@ -1 +1 @@
-1+2
+1 / (74 - 63 + !1) - 74 * 2 / -0.7e+10

src/ir/ir.hpp

@@ -51,6 +51,7 @@ public:
     std::vector<IROpData> IROpDatas;
 
     int parse(ASTNode* ast) {
+        if (!ast) return 0;
         switch (ast->kind) {
             case ASTKind::BinaryExpression:
                 return parseBinaryExpr((BinaryExpressionNode*)ast);
@@ -131,8 +132,8 @@ public:
             default: return 0;
         }
 
-        int left  = parse(bin->Left);
+        int left  = bin->Left  ? parse(bin->Left)  : 0;
-        int right = parse(bin->Right);
+        int right = bin->Right ? parse(bin->Right) : 0;
 
         IROpDatas.push_back({
             op,

src/parser/parser.hpp

@@ -420,16 +420,14 @@ inline ASTNode* Parser::parseExpression(uint16_t precedence) {
     if (!left) return nullptr;
 
     while (true) {
-        auto next = lookahead(1);
+        auto next = currentToken();
         if (next.type == TokenType::RPAREN ||
             next.type == TokenType::SEMICOLON ||
             next.type == TokenType::RBRACE ||
             next.type == TokenType::COMMA)
             break;
 
-        next = lookahead(1);
         if (precedence < next.getPowerOperator()) {
-            nextToken();
             left = parseLeftDenotation(left);
         } else {
             break;
@@ -472,8 +470,9 @@ inline ASTNode* Parser::parseNullDenotation() {
         return bin;
     }
 
-    // Numeric literal — NUD does NOT advance; loop handles it
+    // Numeric literal
     if (ct.type == TokenType::NUMBER) {
+        nextToken();
         LiteralNode* lit = new LiteralNode();
         lit->lexerToken  = ct.token;
         lit->parserToken = ct;
@@ -482,6 +481,7 @@ inline ASTNode* Parser::parseNullDenotation() {
 
     // String literal
     if (ct.type == TokenType::STRING) {
+        nextToken();
         LiteralNode* lit = new LiteralNode();
         lit->lexerToken  = ct.token;
         lit->parserToken = ct;
@@ -490,6 +490,7 @@ inline ASTNode* Parser::parseNullDenotation() {
 
     // Boolean / null literals
     if (ct.is({TokenType::KW_TRUE, TokenType::KW_FALSE, TokenType::KW_NULL})) {
+        nextToken();
         LiteralNode* lit = new LiteralNode();
         lit->lexerToken  = ct.token;
         lit->parserToken = ct;
@@ -498,6 +499,7 @@ inline ASTNode* Parser::parseNullDenotation() {
 
     // Identifier
     if (ct.type == TokenType::IDENTIFIER) {
+        nextToken();
         IdentifierNode* id = new IdentifierNode();
         id->lexerToken     = ct.token;
         id->parserToken    = ct;