fix(bedrock_agentcore_starter_toolkit): type mismatch: api_key_env_var_name declared optional[str] but defaults to false (bool)

[kumburovicbranko682-boop]

Description

The field api_key_env_var_name is annotated as Optional[str] but its default value is False, which is a bool. This is a silent type violation. Any downstream code that performs string operations on this field (e.g., os.environ[api_key_env_var_name] or string formatting) will fail at runtime when the default is used. With mypy configured in strict mode (disallow_untyped_defs, warn_return_any), this will also be flagged as a type error. The intended default is almost certainly None (meaning "not set").

Severity: medium
File: src/bedrock_agentcore_starter_toolkit/create/types.py

Expected Behavior

The code should handle this case properly to avoid unexpected errors or degraded quality.