fix: reset parser state in StreamParser::next

StreamParser::next was missing parsing state reset.
It caused incorrectly parsing the first element of the second and later chunks.
This commit addresses the issue.

include/internal/basic_csv_parser.hpp

@@ -304,6 +304,9 @@ namespace csv {
             void next(size_t bytes = ITERATION_CHUNK_SIZE) override {
                 if (this->eof()) return;
 
+                // Reset parser state
+                this->field_start = UNINITIALIZED_FIELD;
+                this->field_length = 0;
                 this->reset_data_ptr();
                 this->data_ptr->_data = std::make_shared<std::string>();
 

single_include/csv.hpp

@@ -6143,6 +6143,9 @@ namespace csv {
             void next(size_t bytes = ITERATION_CHUNK_SIZE) override {
                 if (this->eof()) return;
 
+                // Reset parser state
+                this->field_start = UNINITIALIZED_FIELD;
+                this->field_length = 0;
                 this->reset_data_ptr();
                 this->data_ptr->_data = std::make_shared<std::string>();
 

single_include_test/csv.hpp

@@ -6143,6 +6143,9 @@ namespace csv {
             void next(size_t bytes = ITERATION_CHUNK_SIZE) override {
                 if (this->eof()) return;
 
+                // Reset parser state
+                this->field_start = UNINITIALIZED_FIELD;
+                this->field_length = 0;
                 this->reset_data_ptr();
                 this->data_ptr->_data = std::make_shared<std::string>();