Implement output routing for stdout, output file, and output directory

[Matographo]

Summary

Support stdout as the default output, file output via -o, and directory output for directory rendering.

Why

Output behavior must be deterministic to make the CLI safe for scripting and file generation.

Deliverables

• stdout default for string and file input
• File output target handling
• Directory output target handling
• Error handling for invalid mode combinations

Acceptance Criteria

• String and file input default to stdout
• Output files and output directories are supported via -o
• Directory input without -o returns a usage error
• Relative structure is preserved for directory output

Dependencies

• Depends on Specify CLI behavior, inspection commands, and exit codes #2
• Depends on Create the base project structure for CLI, engine, parser, evaluator, and config #3
• Depends on Implement input auto-detection for string, file, directory, and stdin #4