fix: resolve circular import issues in SQLAlchemy modules

Create dedicated constants module to break circular import dependencies:

- Extract DDL_RESERVED_WORDS and SELECT_STATEMENT_RESERVED_WORDS to constants.py
- Update preparer.py to import from constants module instead of base.py
- Remove unused imports from base.py to clean up dependencies
- Maintain all existing functionality while improving module structure

This resolves circular import chain:
base.py -> preparer.py -> base.py -> compiler.py -> preparer.py

All linting and type checks pass:
✅ ruff check ✅ ruff format ✅ mypy

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: laughingman7743

pyathena/sqlalchemy/base.py

@@ -12,7 +12,6 @@
     MutableMapping,
     Optional,
     Pattern,
-    Set,
     Tuple,
     Type,
     Union,
@@ -57,287 +56,6 @@
     )
     from sqlalchemy.sql.schema import SchemaItem
 
-# https://docs.aws.amazon.com/athena/latest/ug/reserved-words.html#list-of-ddl-reserved-words
-DDL_RESERVED_WORDS: Set[str] = {
-    "ALL",
-    "ALTER",
-    "AND",
-    "ARRAY",
-    "AS",
-    "AUTHORIZATION",
-    "BETWEEN",
-    "BIGINT",
-    "BINARY",
-    "BOOLEAN",
-    "BOTH",
-    "BY",
-    "CASE",
-    "CASHE",
-    "CAST",
-    "CHAR",
-    "COLUMN",
-    "COMMIT",
-    "CONF",
-    "CONSTRAINT",
-    "CREATE",
-    "CROSS",
-    "CUBE",
-    "CURRENT",
-    "CURRENT_DATE",
-    "CURRENT_TIMESTAMP",
-    "CURSOR",
-    "DATABASE",
-    "DATE",
-    "DAYOFWEEK",
-    "DECIMAL",
-    "DELETE",
-    "DESCRIBE",
-    "DISTINCT",
-    "DOUBLE",
-    "DROP",
-    "ELSE",
-    "END",
-    "EXCHANGE",
-    "EXISTS",
-    "EXTENDED",
-    "EXTERNAL",
-    "EXTRACT",
-    "FALSE",
-    "FETCH",
-    "FLOAT",
-    "FLOOR",
-    "FOLLOWING",
-    "FOR",
-    "FOREIGN",
-    "FROM",
-    "FULL",
-    "FUNCTION",
-    "GRANT",
-    "GROUP",
-    "GROUPING",
-    "HAVING",
-    "IF",
-    "IMPORT",
-    "IN",
-    "INNER",
-    "INSERT",
-    "INT",
-    "INTEGER",
-    "INTERSECT",
-    "INTERVAL",
-    "INTO",
-    "IS",
-    "JOIN",
-    "LATERAL",
-    "LEFT",
-    "LESS",
-    "LIKE",
-    "LOCAL",
-    "MACRO",
-    "MAP",
-    "MORE",
-    "NONE",
-    "NOT",
-    "NULL",
-    "NUMERIC",
-    "OF",
-    "ON",
-    "ONLY",
-    "OR",
-    "ORDER",
-    "OUT",
-    "OUTER",
-    "OVER",
-    "PARTIALSCAN",
-    "PARTITION",
-    "PERCENT",
-    "PRECEDING",
-    "PRECISION",
-    "PRESERVE",
-    "PRIMARY",
-    "PROCEDURE",
-    "RANGE",
-    "READS",
-    "REDUCE",
-    "REFERENCES",
-    "REGEXP",
-    "REVOKE",
-    "RIGHT",
-    "RLIKE",
-    "ROLLBACK",
-    "ROLLUP",
-    "ROW",
-    "ROWS",
-    "SELECT",
-    "SET",
-    "SMALLINT",
-    "START",
-    "TABLE",
-    "TABLESAMPLE",
-    "THEN",
-    "TIME",
-    "TIMESTAMP",
-    "TO",
-    "TRANSFORM",
-    "TRIGGER",
-    "TRUE",
-    "TRUNCATE",
-    "UNBOUNDED",
-    "UNION",
-    "UNIQUEJOIN",
-    "UPDATE",
-    "USER",
-    "USING",
-    "UTC_TIMESTAMP",
-    "VALUES",
-    "VARCHAR",
-    "VIEWS",
-    "WHEN",
-    "WHERE",
-    "WINDOW",
-    "WITH",
-}
-# https://docs.aws.amazon.com/athena/latest/ug/reserved-words.html#list-of-reserved-words-sql-select
-SELECT_STATEMENT_RESERVED_WORDS: Set[str] = {
-    "ALL",
-    "ALTER",
-    "AND",
-    "ARRAY",
-    "AS",
-    "AUTHORIZATION",
-    "BETWEEN",
-    "BIGINT",
-    "BINARY",
-    "BOOLEAN",
-    "BOTH",
-    "BY",
-    "CASE",
-    "CASHE",
-    "CAST",
-    "CHAR",
-    "COLUMN",
-    "COMMIT",
-    "CONF",
-    "CONSTRAINT",
-    "CREATE",
-    "CROSS",
-    "CUBE",
-    "CURRENT",
-    "CURRENT_DATE",
-    "CURRENT_TIMESTAMP",
-    "CURSOR",
-    "DATABASE",
-    "DATE",
-    "DAYOFWEEK",
-    "DECIMAL",
-    "DELETE",
-    "DESCRIBE",
-    "DISTINCT",
-    "DOUBLE",
-    "DROP",
-    "ELSE",
-    "END",
-    "EXCHANGE",
-    "EXISTS",
-    "EXTENDED",
-    "EXTERNAL",
-    "EXTRACT",
-    "FALSE",
-    "FETCH",
-    "FLOAT",
-    "FLOOR",
-    "FOLLOWING",
-    "FOR",
-    "FOREIGN",
-    "FROM",
-    "FULL",
-    "FUNCTION",
-    "GRANT",
-    "GROUP",
-    "GROUPING",
-    "HAVING",
-    "IF",
-    "IMPORT",
-    "IN",
-    "INNER",
-    "INSERT",
-    "INT",
-    "INTEGER",
-    "INTERSECT",
-    "INTERVAL",
-    "INTO",
-    "IS",
-    "JOIN",
-    "LATERAL",
-    "LEFT",
-    "LESS",
-    "LIKE",
-    "LOCAL",
-    "MACRO",
-    "MAP",
-    "MORE",
-    "NONE",
-    "NOT",
-    "NULL",
-    "NUMERIC",
-    "OF",
-    "ON",
-    "ONLY",
-    "OR",
-    "ORDER",
-    "OUT",
-    "OUTER",
-    "OVER",
-    "PARTIALSCAN",
-    "PARTITION",
-    "PERCENT",
-    "PRECEDING",
-    "PRECISION",
-    "PRESERVE",
-    "PRIMARY",
-    "PROCEDURE",
-    "RANGE",
-    "READS",
-    "REDUCE",
-    "REFERENCES",
-    "REGEXP",
-    "REVOKE",
-    "RIGHT",
-    "RLIKE",
-    "ROLLBACK",
-    "ROLLUP",
-    "ROW",
-    "ROWS",
-    "SELECT",
-    "SET",
-    "SMALLINT",
-    "START",
-    "TABLE",
-    "TABLESAMPLE",
-    "THEN",
-    "TIME",
-    "TIMESTAMP",
-    "TO",
-    "TRANSFORM",
-    "TRIGGER",
-    "TRUE",
-    "TRUNCATE",
-    "UNBOUNDED",
-    "UNION",
-    "UNIQUEJOIN",
-    "UPDATE",
-    "USER",
-    "USING",
-    "UTC_TIMESTAMP",
-    "VALUES",
-    "VARCHAR",
-    "VIEWS",
-    "WHEN",
-    "WHERE",
-    "WINDOW",
-    "WITH",
-}
-RESERVED_WORDS: Set[str] = set(DDL_RESERVED_WORDS | SELECT_STATEMENT_RESERVED_WORDS)
 
 ischema_names: Dict[str, Type[Any]] = {
     "boolean": types.BOOLEAN,