actions/upload-artifact@v3 is fully deprecated and causes instant CI
failure. Also upgrades checkout, setup-python, cache, github-script,
and codecov actions to their latest major versions to resolve Node.js 20
deprecation warnings. Adds missing pytest install to MCP Vector DB test
job and pins ruff>=0.15 in CI to match local tooling.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
- Filter out chunks smaller than min_chunk_size (default 100 tokens)
- Exception: Keep all chunks if entire document is smaller than target size
- All 15 tests passing (100% pass rate)
Fixes edge case where very small chunks (e.g., 'Short.' = 6 chars) were
being created despite min_chunk_size=100 setting.
Test: pytest tests/test_rag_chunker.py -v
