refactor: replace config option macros

[ryanfowler]

Summary

• replace the recursive config option macro system with explicit ConfigValues, ConfigField, and CONFIG_OPTIONS definitions
• simplify parse/apply closures and remove redundant closure-call/cloning allowances
• preserve existing config parsing, overlay, and CLI application behavior

Validation

• cargo fmt --check
• cargo clippy --locked --all-targets --all-features -- -D warnings
• cargo test --locked --all-features --lib config::