Generate a QR Code and write it out to io.Writer

GenerateWithConfig expects a string to encode and a config

Generate a QR Code with half blocks and write it out to io.Writer

New tests that actually verify the output Test that captures and verifies the output

Test with various configurations

Test that the same input always produces the same output

Test edge cases

Test that different error correction levels produce different outputs

Original tests that just verify the code doesn't crash

Test that the QR code pattern is consistent and contains the expected pattern

Test the structure of the QR code (size, quiet zone, etc.)

Test that the sixel detection function works