The sixth revision

[habedi]

This revision includes a lot of changes, including bug fixes, API, and efficiency improvements.

• Added trained state management and a pending vector map to PQIVFIndex.
• Added the AllowBruteForceFallback option to PQIVFIndex and RPTIndex to make the fallback to brute-force search explicit. See Revise the API #11
• Added a nodesByLevel map to HNSWIndex for efficient level management on bulk deletes.
• Implemented SIMD distance functions with AVX2 support. Previously, only AVX was supported. See Add support for AVX2 and AVX512 #15
• Refactored NormalizeBatch and buildTreeRecursive for parallel processing to be more efficient.
• Added pre-commit hooks and updated the Makefile for build process improvements inside GitHub Actions environments.
• Refactored distance functions to return errors on invalid inputs instead of panics.
• Added error handling for zero-dimensional indexes and invalid k values.
• Expanded test coverage with new edge cases for distance and normalization functions. See Add more tests #5
• Updated README with training requirements and acknowledgments.

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