Cleaning Code

[kambshu]

• Repackaged everything under core/ (core/algorithms/monte_carlo, core/algorithms/tabular, core/env, core/utils) and moved runnable scripts into examples/; README now documents the layout and updated script paths.
• Hardened core/env/grid_world.py (default obstacle/reward handling and visualization) and cleaned imports/formatting across the codebase with Ruff.
• Added project metadata and dependency management via pyproject.toml, requirements.txt, and an updated environment.yml (Python 3.11, aligned deps).
• Created tooling: Dockerfile, CI workflow .github/workflows/ci.yml (ruff format/check + pytest on main/master), broader .gitignore, and a placeholder test in tests/test_placeholder.py so the test stage is green.