Modernize NRCLex package layout, resource loading, and release tooling

[DemetersSon83]

Motivation

• Move the code from a single fragile module into a proper package so from nrclex import NRCLex remains stable when installed.
• Eliminate cwd-dependent lexicon loading and ensure the bundled nrc_en.json is used reliably when no explicit path is provided.
• Modernize packaging (PEP 517/621), remove bogus stdlib dependencies from metadata, and add packaging/test/release automation and guidance.

Description

• Reorganized repository into a package layout with nrclex/__init__.py (exports NRCLex, sets __version__) and nrclex/core.py (implementation), and moved the lexicon to nrclex/data/nrc_en.json while keeping from nrclex import NRCLex compatible.
• Implemented robust lexicon resolution in the constructor: None → load bundled resource via importlib.resources, explicit existing path → load that file, missing default/relative names → fallback to bundled resource, and missing absolute custom paths raise FileNotFoundError with a helpful message.
• Added caching for lexicon loads via functools.lru_cache and refactored helpers into private methods (_build_word_affect, _compute_top_emotions), introduced EMOTION_ORDER, used Counter and itertools.chain for performance, and added type hints/docstrings.
• Replaced setup.py with pyproject.toml (PEP 517/621), removed stdlib modules from dependencies, set requires-python = ">=3.9", and configured package data so nrclex/data/nrc_en.json is included in sdist/wheel.
• Added deterministic pytest unit tests under tests/ (temporary small lexicons) and an optional integration test for load_raw_text that is skipped when TextBlob/corpora are not available, created a GitHub Actions CI workflow (.github/workflows/ci.yml), and added RELEASING.md and COMPATIBILITY.md.

Testing

• Ran unit tests with PYTHONPATH=. pytest -q -m "not integration" and they passed (all unit tests succeeded).
• Ran the full test suite with PYTHONPATH=. pytest -q and it passed; the integration test is guarded with pytest.importorskip/skip logic and will be skipped automatically if textblob/corpora are not present in the environment.
• Executed a local behavioral congruence check (script comparing outputs for a fixed token list against the legacy logic) which showed identical raw_emotion_scores, affect_frequencies, and top_emotions for the sample tokens.
• Packaging/installation validation (pip install -e ., python -m build, twine check dist/*) could not be completed in this environment because build tools/network access were unavailable or setuptools/build/twine were not installable due to network/proxy restrictions; these steps are included in CI and RELEASING.md for use in a network-enabled environment.

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Codex Task