Implement the settings namespace for -s / --settings

[Matographo]

Summary

Separate parser, engine, cache, and CLI settings from template rules while preserving deterministic override behavior.

Why

Rules and settings serve different purposes and must not bleed into each other semantically.

Acceptance Criteria

• Settings do not override template rules implicitly
• Last write wins within the settings namespace
• Settings can be inspected independently

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