Add CI/CD Pipeline (GitHub Actions + GitLab CI)

[vladiant]

Summary

Adds continuous integration pipelines for both GitHub Actions and GitLab CI, covering Python lint/type-check/test and C++ build/lint. Also fixes a potential integer overflow bug in the C++ extension caught by clang-tidy.

Changes

Added

• GitHub Actions (workflows)
  • python.yml — ruff lint + format check, mypy type checking, pytest with coverage (≥75%) on Python 3.11 and 3.12
  • cpp.yml — CMake build with GCC and Clang matrix, clang-tidy lint (triggered only on cpp changes)
• GitLab CI (.gitlab-ci.yml) — mirrors the GitHub Actions setup with equivalent lint, test, and build stages
• pytest-cov added to dev dependencies (requirements-dev.txt, pyproject.toml)

Fixed

• Integer overflow in fast_resize.cpp: static_cast<size_t>(src_w * src_h * channels) cast after multiplication; fixed to static_cast<size_t>(src_w) * src_h * channels to prevent overflow before widening (caught by bugprone-misplaced-widening-cast)

Files Changed

File	Change
python.yml	New — Python CI workflow
cpp.yml	New — C++ CI workflow
.gitlab-ci.yml	New — GitLab CI pipeline
CHANGELOG.md	Added entries for CI and bugfix
pyproject.toml	Version bump 1.0.2 → 1.1.0, added pytest-cov
requirements-dev.txt	Added pytest-cov
fast_resize.cpp	Fixed widening cast bug

Testing

• All 30 tests pass
• ruff check/format, mypy — all clean
• C++ builds with both GCC and Clang
• clang-tidy passes with bugprone-* as errors

Version Bump

MINOR 1.0.2 → 1.1.0 — new CI features + bugfix