Add: Clap commands

[Escoto]

Description

• Add CLI interface with clap: --config-file, --log-level, --validate, --help, --version
• Add config subcommand tree: show, validate, path, init, get, set with dotted-path addressing
• Add interactive overwrite prompt for config init

Relates to #6

Checklist

• Tests added or updated
• cargo clippy -- -D warnings passes
• cargo fmt --check passes
• Documentation updated (if applicable)
• Linked to issue Configuration Wizard #6