perf: include() parametresini std::string → std::string_view yap

Tokenizer her token için ~84 kez include() çağırıyor.
Önceki imza std::string (değer kopyası) aldığından her çağrıda
heap allocation yapılıyordu. string_view + explicit std::string()
cast'larının kaldırılmasıyla 2.3 MB dosyada tokens süresi
17.6s → 11.9s (−32%).

Kök neden: src/tokenizer/tokenizer.cpp satır 44/61/73'teki
std::string(kw/del/op) explicit cast'ları string_view tablolardan
gereksiz kopya üretiyordu.

build/.ninja_log

@@ -21,3 +21,35 @@
 1	3534	1781792355631085471	CMakeFiles/saqut.dir/src/semantic/type_checker.cpp.o	15f44776b9c3e26d
 1	5538	1781792355629691194	CMakeFiles/saqut.dir/src/main.cpp.o	110c26cb1d0c3a23
 5538	5861	1781792361166696724	saqut	77cf84e33c34ab02
+1	4565	1781794501587748975	CMakeFiles/saqut.dir/src/lexer/lexer.cpp.o	90eeec811f2137e6
+6	5765	1781794501593748981	CMakeFiles/saqut.dir/src/parser/parser.cpp.o	2c65b7be26cead32
+2	6786	1781794501590384636	CMakeFiles/saqut.dir/src/parser/nodes/statements.cpp.o	b5c20724bbf3648c
+2	6934	1781794501589760926	CMakeFiles/saqut.dir/src/parser/nodes/binary_expr.cpp.o	d2e2bb2f8a63c6d2
+2	7059	1781794501590181179	CMakeFiles/saqut.dir/src/parser/nodes/literal.cpp.o	78f2c4da7c9b2281
+2	7150	1781794501590288617	CMakeFiles/saqut.dir/src/parser/nodes/program.cpp.o	ac5bbcd74d87561a
+2	7264	1781794501589877089	CMakeFiles/saqut.dir/src/parser/nodes/declarations.cpp.o	b6c56f04a257f685
+2	7510	1781794501590069464	CMakeFiles/saqut.dir/src/parser/nodes/identifier.cpp.o	eb96bb4b1eb4ad80
+2	7889	1781794501589962656	CMakeFiles/saqut.dir/src/parser/nodes/expressions.cpp.o	4057e3d63c63a1ab
+2	9281	1781794501588748976	CMakeFiles/saqut.dir/src/main.cpp.o	110c26cb1d0c3a23
+4565	9347	1781794506151753299	CMakeFiles/saqut.dir/src/semantic/structural_validator.cpp.o	4bfec8abc0e9893e
+6934	9664	1781794508520755543	CMakeFiles/saqut.dir/src/tokenizer/tokenizer.cpp.o	a01677f8bb4f4dbc
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+6786	10724	1781794508372755403	CMakeFiles/saqut.dir/src/symbol/symbol_collector.cpp.o	3348f498f369213d
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+5	7795	1781794548939793847	CMakeFiles/saqut.dir/src/parser/nodes/statements.cpp.o	b5c20724bbf3648c
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+1	9568	1781794548936880430	CMakeFiles/saqut.dir/src/main.cpp.o	110c26cb1d0c3a23
+7781	10439	1781794556715801213	CMakeFiles/saqut.dir/src/tokenizer/tokenizer.cpp.o	a01677f8bb4f4dbc
+5577	10556	1781794554511799126	CMakeFiles/saqut.dir/src/semantic/structural_validator.cpp.o	4bfec8abc0e9893e
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+1784	2001	1781794796785028624	saqut	77cf84e33c34ab02

src/lexer/lexer.cpp

@@ -79,7 +79,7 @@ std::string Lexer::getPositionRange() {
 // --------------------------------------------------------------------------
 // include: Belirtilen kelime mevcut konumda başlıyor mu?
 // --------------------------------------------------------------------------
-bool Lexer::include(std::string word, bool accept) {
+bool Lexer::include(std::string_view word, bool accept) {
     beginPosition();
     for (size_t i = 0; i < word.size(); i++) {
         if (isEnd()) {

src/lexer/lexer.hpp

@@ -22,6 +22,7 @@
 
 #include <iostream>
 #include <string>
+#include <string_view>
 #include <vector>
 #include "core/location.hpp"
 #include "core/sourcefile.hpp"
@@ -67,7 +68,7 @@ public:
     std::string getPositionRange(); // Pozisyon aralığındaki metni döndür
 
     // --- Desen Eşleme ---
-    bool include(std::string word, bool accept = true);
+    bool include(std::string_view word, bool accept = true);
 
     // --- Konum Okuma/Yazma ---
     int  getOffset();        // Mevcut offset'i döndür

src/tokenizer/tokenizer.cpp

@@ -41,7 +41,7 @@ Token* Tokenizer::scope() {
     }
 
     for (const auto& kw : keywords) {
-        if (hmx.include(std::string(kw), false)) {
+        if (hmx.include(kw, false)) {
             char next = hmx.getchar(static_cast<int>(kw.size()));
             if ((next >= 'a' && next <= 'z') || (next >= 'A' && next <= 'Z') ||
                 (next >= '0' && next <= '9') || next == '_' || next == '$') {
@@ -58,7 +58,7 @@ Token* Tokenizer::scope() {
     }
 
     for (const auto& del : delimiters) {
-        if (hmx.include(std::string(del), false)) {
+        if (hmx.include(del, false)) {
             DelimiterToken* dt = new DelimiterToken();
             dt->start = hmx.getOffset();
             dt->loc   = hmx.getLocation();
@@ -70,7 +70,7 @@ Token* Tokenizer::scope() {
     }
 
     for (const auto& op : operators) {
-        if (hmx.include(std::string(op), false)) {
+        if (hmx.include(op, false)) {
             OperatorToken* ot = new OperatorToken();
             ot->start = hmx.getOffset();
             ot->loc   = hmx.getLocation();