- Introduce `index.rs` for file indexing using SQLite
- Expand configuration options in `config.rs`, including `excluded_files`
- Update dependencies in `Cargo.toml` to include SQLite, hashing, and regex libraries
- Introduced `walk.rs` as a parallel directory walker for search operations.
- Implemented basic index handling in `commands/index.rs`.
- Created `utils/config.rs` for configuration management with placeholders for future enhancements.
