Fixed bugs and made improvements

[izumicancode]

Implemented two new search capabilities for Blackbird:

1. Close Username Variant Matching

• Added --check-variants support.

• Checks the exact username plus ~25 realistic variations, including:

  • Trailing _, ., and numbers
  • the / real prefixes
  • Common separator variations

• Results now clearly label matches as exact, close, or variant.

• Example: hussainography can now detect a match such as hussainography_.

2. Region-Based Platform Filtering(needs improvements)

• Added --region support, e.g. --region russia|china|japan|korea.
• Filters the site list to platforms commonly used in the selected region.
• This is intentionally a platform-selection filter, not account-level geolocation.
• No false claims are made about being able to search Instagram or other platforms for accounts by city/country.

Additional Fixes

• Fixed a false-positive issue where LINE could match inside unrelated words such as online.
• Added proper word-boundary matching.
• Tested both features through full interactive walkthroughs with no crashes.
• Updated the README with usage examples and limitations.
• Made a new Filter system to show results only from a seleted site.
• Perfected the Instagram search.

Testing

Both features were tested individually and together with the existing --filter functionality. The interactive flows completed successfully without crashes.

Notes

The region feature intentionally does not attempt to infer an account's location. It only narrows which platforms are searched, keeping the behavior transparent about what external platforms actually allow.