Refactor: Reorganize project to advanced senior-level structure

Solve: Problem #3 - Longest Substring Without Repeating Characters

Fix: Format C++ assert statements to satisfy clang-format

Fix: Resolve GitLab CI pipeline failures

Fix: Rewrite GitLab CI with separate Python version jobs

Add GitLab CI/CD configuration and update documentation

Fix: Make Python cache cleaning and test execution Windows-compatible

Improve: Use importlib mode and fallback for pytest test discovery

Fix: Resolve pytest import conflicts for test files with same name

Fix: Change main() docstring to imperative mood for flake8 compliance

Fix: Resolve all flake8 linting errors

Fix: Resolve signed/unsigned comparison warning in Two Sum C++ solution

Refactor: Enterprise-grade repository structure and add problem #2

update README

Minor Updates