Add comprehensive INSERT parser tests with round-trip verification

32 new tests covering MySQL and PostgreSQL INSERT/REPLACE:
- Basic VALUES, multi-row, column list, INSERT SELECT, INSERT SET
- ON DUPLICATE KEY UPDATE, IGNORE, LOW_PRIORITY, DELAYED, HIGH_PRIORITY
- REPLACE with various options
- PostgreSQL ON CONFLICT DO NOTHING/UPDATE, RETURNING, DEFAULT VALUES
- Bulk data-driven tests (24 MySQL + 16 PostgreSQL variants)
- Round-trip emitter tests (7 MySQL + 5 PostgreSQL)

Also fixes is_alias_start() to block TK_LPAREN which was incorrectly
treated as a valid implicit alias token.

Total test count: 268 (was 236, +32 new)

Author: renecannao

Makefile.new

@@ -27,7 +27,8 @@ TEST_SRCS = $(TEST_DIR)/test_main.cpp \
             $(TEST_DIR)/test_set.cpp \
             $(TEST_DIR)/test_select.cpp \
             $(TEST_DIR)/test_emitter.cpp \
-            $(TEST_DIR)/test_stmt_cache.cpp
+            $(TEST_DIR)/test_stmt_cache.cpp \
+            $(TEST_DIR)/test_insert.cpp
 TEST_OBJS = $(TEST_SRCS:.cpp=.o)
 TEST_TARGET = $(PROJECT_ROOT)/run_tests
 

include/sql_parser/table_ref_parser.h

@@ -208,6 +208,7 @@ class TableRefParser {
             case TokenType::TK_UNION:
             case TokenType::TK_SEMICOLON:
             case TokenType::TK_RPAREN:
+            case TokenType::TK_LPAREN:
             case TokenType::TK_EOF:
             case TokenType::TK_COMMA:
             case TokenType::TK_SET: