Code-review

[gouyt13]

Summary

• Make packed-factor access and aligned storage ownership safe while preserving contiguous QG rows and persisted formats.
• Fix IVF inner-product cluster routing and pruning inputs.
• Validate index state, search parameters, allocation sizes, and file contents; preserve existing indexes on failed loads.
• Correct SIMD feature detection, unaligned accesses, and worker cleanup.
• Fix clang-tidy include ordering.

Validation

• ASan/UBSan: 133/133 passed with native optimization off and leak detection disabled.
• NoPython: 132/132 passed against the rebuilt extension.
• Clang 15 analysis: 20/20 library/binding translation units passed.
• Formatting, Python lint, ShellCheck, whitespace checks, and strict documentation build passed.