Email-based scanning support

Category: core-feature

Goal: Implement email scanning capabilities as a separate module from username scanning.

Task Checklist:

• Create new directory structure under user_scanner/email_scan/
• Implement email-specific scanning methods and modules
• Update user_scanner/core/orchestrator.py to support email validation logic
• Add -e / --email argument to main.py (Ensure -e is mutually exclusive with -p and other username-specific arguments)
• Tweak Result and Printer classes for email-specific output
• Add initial email validation functions (e.g., check_)
• Move existing site modules into the new username_scan structure

Project tree should be like the below.

└── 📁user-scanner
    └── 📁tests
    └── 📁user_scanner
        └── 📁username_scan
            ├── 📁community
            ├── 📁creator
            ├── 📁dev
            ├── 📁donation
            ├── 📁gaming
            └── 📁...
        └── 📁email_scan
            ├── 📁community
            ├── 📁creator
            └── 📁...
        └── 📁cli
        └── 📁core
        └── 📁utils
        ├── __init__.py
        ├── __main__.py
        ├── config.json
        ├── version.json
    ├── .gitignore
    ├── CONTRIBUTING.md
    ├── ...

Implementation notes:

• Keep email modules isolated from existing username modules.
• Ensure the argument parser (argparse) uses mutually exclusive groups or logic to prevent mixing -e with username-only arguments.