feat(cli): add banking system cli app and fix #166

[AksharGoyal]

Banking System

Description

A small CLI banking system written in Rust for learning and demo purposes.
Provides account creation, login, simple operations and account deletion via a single binary.

Features:

• Create accounts with randomly generated 10-digit account numbers and 6-digit PINs
• Login using account number + PIN
• Delete accounts
• Persistent storage using SQLite (via rusqlite) so accounts survive between runs
• CLI parsing and subcommands handled with clap for a familiar UX and easy extension
• Random data generation uses rand for account numbers and PINs

Dependency mapping (from Cargo.toml):

• clap — command-line parsing and subcommands
• rand — secure-ish random generation for account numbers and PINs
• rusqlite — persistent SQLite backend (database file is created in the working directory by default)

Tech Stack

• Language: Rust
• Build / package manager: cargo
• CLI parsing: clap
• Random generation: rand
• Persistence: rusqlite
• Testing: cargo test
• Formatting: rustfmt (cargo fmt)
• Linting: clippy (cargo clippy)

This contribution is part of Hacktoberfest 2025.